What is the Nationality and Borders Bill, why is it so controversial and what do MPs want to change?

This week, the Nationality and Borders Bill returns to the Commons for two days of scrutiny.

Ministers describe the legislation as "the cornerstone of the government's New Plan for Immigration, delivering the most comprehensive reform in decades to fix the broken asylum system".

But the Joint Committee on Human Rights (JCHR) - headed up by the longest serving female member of the Commons Harriet Harman - has been very critical of the bill and many amendments have been tabled to it.

The bill's return on Tuesday comes under renewed scrutiny following the rising number of migrant crossings taking place in recent weeks, with over 25,000 arriving via the Channel so far this year.

In November, more than 1,000 people arrived in a single day for the first time. And tragically, 27 people drowned in the deadliest crossing on record.

One area of concern that has been raised is that new measures within the legislation to criminalise attempts by individuals without visas to enter the UK would breach human rights law, and the JCHR have laid amendments with that in mind.

As of 6 December, 88 pages of amendments had been tabled. The chair will ultimately decide which of these will be debated and voted on.

What does the government say the Nationality and Borders Bill will do?

Priti Patel said the government's Nationality and Borders Bill would tackle illegal immigration and the "underlying pull factors into the UK's asylum system".

Ministers have said the legislation has three main objectives:

• To make the system fairer and more effective so that we can better protect and support those in genuine need of asylum.

• To deter illegal entry into the UK breaking the business model of criminal trafficking networks and saving lives.

• To remove from the UK those with no right to be here.

The government says the bill is necessary because in 2019, UK asylum applications increased by 21% on the previous year to almost 36,000, the current appeals system is too slow and the system costs "over £1bn a year to run".

They add that the number of people with no right to be in the UK being removed has been steadily declining due to legal challenges, and that "as a result, there are now over 10,000 foreign national offenders circulating on the streets, posing a risk to the public".

What concerns have been raised?

Human rights organisation Amnesty International say, if passed, the Nationality and Borders Bill "will create significant obstacles and harms to people seeking asylum in the UK's asylum system" and that the legislation undermines the Refugee Convention and the UK's obligations under the Convention on the Rights of the Child and the Convention on Reduction of Statelessness.

In October, a team of leading immigration lawyers also concluded that the controversial bill breaches international and domestic law in at least 10 different ways and accused the government of "riding roughshod" over its obligations.

Leading the team, human rights QC Raza Husain said, if passed, the legislation will lead to challenges under international human rights and refugee treaties.

"This bill represents the biggest legal assault on international refugee law ever seen in the UK," a report from the human rights group Freedom From Torture concluded.

The same group said government plans to send those claiming asylum to offshore centres would breach three articles of the European Convention on Human Rights.

Ms Patel said the legislation would authorise "boat turnarounds" amid a sharp rise in people making perilous journeys across the English Channel and would give Border Force staff who commit criminal offences while pushing back boats immunity from prosecution.

But the JCHR argue that "push backs are not the solution".

"They will not deter crossings, the seas will become even more dangerous and the people smugglers will continue to evade punishment," Ms Harman has previously said.

"Current failures in the immigration and asylum system cannot be remedied by harsher penalties and more dangerous enforcement action."

The government disagrees with the above claims, saying the new immigration plan "complies with all our international obligations, including under the European Convention on Human Rights and the UN refugee convention".

What are some of the key amendments?

A plethora of amendments have been tabled to the Nationality and Borders Bill.

One prominent proposal is New Clause 9, an amendment put forward by Labour's Meg Hillier but also co-signed by Conservative's Peter Bottomley and David Simmons, which would require the government to issue a physical certificate when granting settled status or pre-settled status under the EU Settlement Scheme.

Another, New Clause 8 - a largely Labour-backed amendment - would prevent the Home Office from charging a fee which exceeds the cost of processing an application for a child registering as a British citizen.

Then there is an amendment which, interestingly, is mostly supported by opposition MPs including former cabinet ministers David Davis and Andrew Mitchell that would remove provisions allowing asylum claims to be processed in another country.

This comes after Justice Secretary Dominic Raab did not deny to Sky News last month that ministers are hoping to secure a deal to fly migrants who cross the Channel on small boats to Albania.

It came after The Times reported that ministers are hoping to seal an agreement to fly Channel-crossing migrants to the southeast European country for offshore processing within seven days of arrival on British beaches.

It is suggested that the prospect of a long wait there while asylum claims are evaluated would act as a deterrent against making the treacherous journey.

Other notable amendments include one by former Conservative minister Damian Green and supported by Tory chair of the Foreign Affairs Committee Tom Tugendhat which would ensure individuals from Hong Kong only need to have one parent with British National Overseas (BNO) status to apply for a BNO visa.

New Clause 4 would similarly allow all former British-Hong Kong service personnel and their partners the right to live in the UK.

Also regarding citizenship, New Clause 2 would allow anyone who has descended from a person born before 1983 on the British Indian Ocean Territory to register as a British Overseas Territories Citizen.

Elsewhere, Conservative Christopher Chope - backed by other Tory MP including Philip Hollobone, Esther McVey and Philip Davies - have a new clause which would make it an offence to enter the UK illegally and remain without permission.

Their New Clause 18 says anyone who does so should be able potentially liable to "imprisonment for a term not exceeding 12 months or a fine (or both)".