By Bozorgmehr Sharafedin
LONDON (Reuters) - Pro-government rallies in several Iranian cities drew thousands of marchers on Wednesday, following six days of rare unrest that took the country's leaders off guard.
State television broadcast live pictures of rallies in Kermanshah, Ilam and Gorgan, where marchers waved Iranian flags and pictures of Supreme Leader Ayatollah Ali Khamenei.
The boldest challenge to Iran's established order in almost a decade had continued into Tuesday night, with postings and video footage on social media showing riot police deployed in force in several cities.
Hours earlier, Khamenei accused Iran's foes of fomenting the unrest.
On Wednesday, marchers voiced their support for Khamenei, chanting: "The blood in our veins is a gift to our leader" and "We will not leave our leader alone".
The protests, which began over economic hardships, have taken on a rare political dimension, with a growing number of young people calling on Khamenei to step down.
They are the biggest since unrest in 2009 that followed the disputed re-election of then-President Mahmoud Ahmadinejad.
At least 21 people have been killed during the unrest, including two members of the security forces.
More than 450 protesters have been arrested in the capital Tehran in recent days, and hundreds of others were detained around the country, according to officials. A judicial official said some could face the death penalty.
"The seditionist rioters should be executed," marchers chanted on Wednesday, while posters they carried said hostile "hidden hands" guided from the United States, Israel and the United Kingdom should be cut off.
In at attempt to control the flow of information and calls for anti-government gatherings, Tehran authorities have restricted access to the Telegram messaging app and Instagram, owned by Facebook Inc.
High prices, alleged corruption and mismanagement are fuelling the anger.
President Hassan Rouhani championed a deal struck with world powers in 2015 to curb Iran's nuclear program in return for the lifting of most international sanctions.
However, he has failed to deliver on promises of prosperity in the OPEC oil producer where youth unemployment reached 28.8 percent last year.
The nuclear deal is facing its biggest challenge since it was struck, with U.S. President Donald Trump due to decide by mid-January whether to continue waiving U.S. sanctions or reimpose them.
(Reporting by Bozorgmehr Sharafedin; editing by John Stonestreet)