The Foreign Office has been accused of allowing government asylum policy to be dictated to by a Pakistan mob after it was confirmed it urged the Home Office not to grant Asia Bibi political asylum in the UK out of fear for the safety of UK consular staff.

Asia Bibi, a Christian woman acquitted of blasphemy, is seeking asylum after threats to her life in Pakistan. The former UK foreign secretary Boris Johnson was among many MPs calling for her and her family to be granted sanctuary in Britain.

The acquittal of the 53-year-old Catholic farmworker by Pakistan’s supreme court last month prompted demonstrations by hardline Islamist parties in Pakistan who had campaigned for her to be hanged.

She remains in protective custody in an undisclosed locationin Pakistan after the prime minister, Imran Khan, agreed to allow a petition against the court’s decision as part of a deal to halt the protests.

Her husband, Ashiq Masih, has appealed for help to Britain, Canada, Italy and the US but the UK high commissioner in Islamabad is reported to have warned he could not protect his staff if asylum was granted by the UK.

Tom Tugendhat, the foreign affairs select committee chair, asked the Foreign Office permanent secretary, Sir Simon McDonald, whether the episode “does not raise the question that either staff should be withdrawn or security increased or otherwise UK policy is effectively dictated to by a mob?”.

Tugendhat took the committee into lengthy private session after McDonald said he did not wish to give evidence in public on a such a sensitive issue

McDonald defended Britain’s efforts to find a third country to take Bibi, saying this would allow UK policy objectives to be achieved without any risk to its staff.

Tugendhat said the episode represented “one of the clearest examples of free conscience being challenged today”.

The senior Labour MP Mike Gapes said: “Given the clear inability of this new Pakistani government of Imran Khan to stop these mobs from intimidating and killing Christians in Pakistan, is it not time to reassess our relations with Pakistan? There are big concerns if religious minorities in Pakistan are not safe.”

McDonald said the Britain’s relationship with Pakistan relationship was important to both countries.

He added: “If the objective is to protect life and some other country can provide some more complete safe harbour, why should the UK not be open to working with that country?”

The Pakistan foreign office confirmed on Tuesday that it had been holding talks with the Canadian foreign ministry over granting Bibi asylum.

Confirmation of talks between the two governments came after the Canadian prime minister, Justin Trudeau, said on Monday his government was talking to Pakistan about the case.

“We are in discussions with the Pakistani government,” Trudeau said in an interview with Agence France-Presse (AFP) in Paris, where he was attending a peace conference organised by the French president, Emmanuel Macron.