House Judiciary Committee issues subpoenas to former White House staffers Hope Hicks and Annie Donaldson

The House Judiciary Committee has subpoenaed former White House communications director Hope Hicks and a former aide in the White House counsel's office.

The subpoenas come as part of an investigation into whether President Donald Trump and members of his administration obstructed justice, the committee said.

The committee subpoenaed Ms Hicks for documents and for testimony at a public hearing. It subpoenaed Annie Donaldson, former chief of staff to ex-White House counsel Don McGahn, for documents and for questioning in a private deposition.

The subpoenas, authorised last month, call on Ms Hicks and Ms Donaldson to produce requested documents early next month.

House Judiciary Committee Chairman Jerrold Nadler was quoted as saying last month: "We believe that these individuals may have received documents from the White House in preparation for their interviews with the special counsel.

"We also believe that these individuals may have turned this information over to their private attorneys."

Ms Donaldson was a top aide to Mr McGahn, who on Tuesday defied a subpoena from the committee to testify.

Mr McGahn, who played a key role in Special Counsel Robert Mueller’s two-year probe, was directed not to appear by Mr Trump.

According to Mr Mueller’s report, the White House lawyer was told by Mr Trump to axe Mr Mueller but refused.

He then said he was pressured to deny that the president ever sought to remove the special counsel.

Although the report, released last month, cleared the Trump campaign of colluding with Russia before the 2016 election, it listed 10 instances of possible obstruction of justice by the president.

More Democrats are calling for impeachment proceedings against Mr Trump after he blocked Mr McGahn from testifying.

A growing number of rank-and-file House Democrats, incensed by former counsel Mr McGahn's empty chair in the hearing room, are pushing House Speaker Nancy Pelosi and other leaders to act.

Their impatience is running up against the speaker's preference for a more methodical approach, including already-unfolding court battles.

Ms Pelosi has summoned them to a meeting on Wednesday to assess strategy.

Some other Democratic leaders, while backing Ms Pelosi, signalled that a march to impeachment may at some point become inevitable.

Majority Leader Steny Hoyer says if a House inquiry "leads to other avenues including impeachment ... so be it."