Ministers “deeply distressed” Nazanin Zaghari-Ratcliffe and other British citizens imprisoned abroad through poor communication, including “speaking offensively” to their families, the Conservative chairwoman of the Commons Foreign Affairs Committee has said.

Speaking about a damning new report on the Foreign Office’s handling of hostage diplomacy, Alicia Kearns said the treatment of some hostages and their relatives had been “insensitive and hurtful”, marked by a lack of transparency and coordination.

Referring to former foreign secretary Liz Truss’s handling of the case of a British-born environmentalist held in Iran, she said “the most heinous failure of a minister” was to tell a family “you’re no longer our problem”.

Ms Truss did not stand by an arrangement agreed with US officials that UK-US-Iranian trinational Morad Tahbaz would be released alongside Mrs Zaghari-Ratcliffe and fellow British-Iranian dual national Anoosheh Ashoori in March last year, and failed to let his family know, according to the report.

“Liz Truss eventually called the family to say that ‘Morad is now a US problem’, implying that she would not put further effort into his release, and she did not have time to speak to them further,” MPs said.

The report also highlighted then-foreign secretary Boris Johnson saying in 2017 that Mrs Zaghari-Ratcliffe had been teaching journalism in Tehran, comments which were blamed for exacerbating her plight following her arrest for alleged spying.

There were also examples of ministers “getting the names of hostages wrong”, Ms Kearns told Times Radio.

“For dual nationals their Britishness too often they felt was in question,” she said.

The report also criticised the “considerable ministerial transience” in recent years, with Ms Zaghari-Ratcliffe questioning, on her release, why it took five foreign secretaries over six years to bring her home.

“This contributes to inconsistency of approach and increases the risks of missing opportunities, not least when dealing with autocratic states with greater ministerial security of tenure,” MPs said.

The committee called for a director for arbitrary and complex detentions.

“That is somebody who would have a direct line to the prime minister, who can make sure that we have the cohesion, the continuity, the focus, the creativity that is needed to get our people home,” Ms Kearns said.

“Because the reality is that one of our most important findings was if you can get people home before they are charged, that is your best window of opportunity.”

The senior Tory also said “we have to call a spade a spade”, as there is currently “too much nervousness within the Foreign Office about calling out state hostage-taking for what it is”.

The committee rejected a Foreign Office presumption that “quiet diplomacy” and family silence is always appropriate, saying that other than in the initial phase, “silence abets state hostage-taking”.

Amnesty International welcomed the findings of the report, “which should lead to a major policy change”.

Sacha Deshmukh, the charity’s UK chief executive, said: “Year after year during Nazanin Zaghari-Ratcliffe and Anoosheh Ashoori’s gruelling incarcerations we were warning that the UK simply wasn’t rising to the challenge of dealing with situations that went well beyond ordinary miscarriages of justice…

“The test of whether UK officials have learnt from previous failings will be whether they can be effective in quickly securing the release of the jailed conservationist Morad Tahbaz and fellow Briton Mehran Raoof, as well as another British national, Alaa Abd el-Fattah, who’s been jailed in Egypt for his human rights work.”

A Foreign, Commonwealth and Development Office spokesman said: “Consular officials are available 24/7 for families to receive tailored support. The Foreign Secretary and FCDO ministers are fully engaged in complex cases and have raised concerns with foreign governments.

“The best interests of British national detainees is at the heart of our consular work and we support and work with their families wherever we can.”