The Home Secretary will be grilled over her involvement in parts of a controversial US report on CIA interrogation techniques which were hidden from the public.
Theresa May faces questions over her role in the parts which were redacted from the American Senate's damning report on torture techniques used by the CIA after 9/11.
MPs on the influential Home Affairs select committee want to know whether she asked for sections to be blacked out because they could embarrass Westminster.
Downing Street confirmed the Home Secretary met with the committee behind the US report and the encounter would have covered a "wide range of issues".
However, MPs are in the dark over the extent of the UK's involvement in the torture of terror suspects and want to know if former Prime Minister Tony Blair and his Foreign Secretary Jack Straw were in anyway complicit.
Mrs May will appear in front of the committee at 4:30pm.
Shadow home secretary Yvette Cooper says that there must be a judge-led public inquiry into the UK's role in a brutal and ineffective CIA-led interrogation and torture programme.
Speaking on Andrew Marr's BBC show, Ms Cooper said: "My instinct has always been that it would be the right thing to do."
Former or serving ministers may be called to give evidence over allegations of British involvement in torture, Sir Malcolm Rifkind has said.
Rifkind, the head of the Intelligence and Security Committee (ISC), said if UK agents were present when detainees were being tortured, it "would be quite against all standards of this country" and should be made public.
"If people deserve to be embarrassed, it's our job to embarrass them," he added.
Asked whether he could call ex-Prime Minister Tony Blair, David Miliband or Jack Straw to give evidence, Sir Malcolm Rifkind said: "We will request any former or serving minister who has a contribution to make to our inquiry to give evidence."
If ministers refuse to appear, it will imply they "have something to hide", Rifkind said.
Former Prime Minister Tony Blair and ex-Foreign Secretary Jack Straw should give evidence to a parliamentary panel about Britain's alleged links to torture if required, Alan Johnson has said.
The former Home Secretary said the UK must obtain the damning report into the CIA's post-9/11 interrogation programme in full to examine the UK's alleged involvement.
Mr Johnson told the BBC's Andrew Marr Show that he and ex-Foreign Secretary David Miliband conducted a "thorough investigation" into allegations of torture while they were in government.
"We could find no evidence of British agents being involved [in torture]," he said.
"I'm absolutely convinced that what was redacted, was what the Home Office says they wanted redacted."
The parliamentary panel investigating allegations of British involvement in torture following 9/11 has asked to see secret material from a damning CIA report.
Intelligence and Security Committee (ISC) chair Sir Malcolm Rifkind requested any redacted sections relating to the UK's role in the interrogation of terror suspects.
Sir Malcolm said it was for the US Government to decide whether to supply the material.
Asked if he was hopeful of success, he said: "I do not say I would be confident."
Downing Street has confirmed British spies spoke to their US counterparts to discuss blacking out some sections.
But it insisted it related only to "national security grounds" and was not to cover-up British complicity in torture.
The mother of black teenager Michael Brown, who was shot dead by police in Ferguson, said she hopes the protests sparked by his death will make a difference.
Lesley McSpadden said she was overwhelmed by the "sea of people" as thousands turned out to take part in a march on Washington.
She added: "If they don't see this and make a change, I don't know what we're going to do."
Nearly two dozen civil rights protesters have been arrested in Boston in the US.
Police said the demonstrators were detained for disorderly conduct after trying to block a highway.
Thousands are taking part in protests in New York, Washington and California, which have so far remained peaceful.
It comes after three unarmed black men were killed by police in recent weeks.
Hundreds of protesters have gathered near New York's Washington Square Park, to join a march against "police brutality" following the recent deaths of two unarmed black men at the hands of white police officers.
Bearing signs emblazoned with the slogan 'stop police brutality' the crowd marched towards NYC's police headquarters chanting "I can't breathe", the dying words of police choke-hold victim Eric Garner.
The New York march coincides with another 'justice for all' march being held in Washington today.
Thousands of demonstrators streamed through the streets of Washington singing, shouting and chanting against the recent police killings of unarmed black men.
Shouts of 'Black lives matter', 'Hands up, don't shoot', and 'I can't breathe' were heard as a wide range of Americans from different ethnic backgrounds walked peacefully through the capital.
Crowds of protesters have filled the streets leading up to Washington's capitol hill as they march for 'justice for all' following the deaths of two unarmed black men at the hands of white police officers.
Carrying signs which read "Black Lives Matter" and "Who do you protect? Who do you serve?", the crowd gathered in Freedom Plaza today before marching up the capital's Pennsylvania Avenue.