Ros Altmann has described her time as David Cameron's Pensions Minister as "the most terrible experience", and claimed that her health suffered because of the stress of being "silenced" by government officials.

Baroness Altmann, who stepped down from the role last Friday following Mr Cameron's departure from Downing Street, said that leaving government would allow her to be more influential.

She explained: "It has been the most terrible experience for me. I have felt under pressure the whole time; you have been squished and squashed in every direction and you just want to explode sometimes. It affected my health without question. It's a very uncomfortable experience."

The peer, a member of Finchley United Synagogue in north London, has spoken about the importance of Orthodox women in leadership. But she said that as a minister she had been "micro-controlled".

"I can do more good from the outside because I won't be silenced anymore," she added.

I was not able to explain policy in an open way

The 60-year-old said she had been frustrated by the government press office's attitude to the media. As the former director-general of Saga Group, she said she regularly used the media to discuss policy issues.

Baroness Altmann revealed that during her 14 months in government she was "not allowed to speak to the media; it is all done through the press office who often do not understand pensions.

"The instructions I had were: 'If any journalist phones you; then they are always out to trick you and trap you'.

"What I found difficult was not being able to explain policy to the media; and thereby to the public in an open and honest way; which is what I have always done."

She added: "Now and again I was very naughty, and I would actually speak to a journalist and take the consequences because I thought: 'Stuff it, I have had enough of this'.

"But then you get called in to see the Secretary of State. It's like being in school, like being in the naughty corner or detention."

Baroness Altmann said that earlier this year she had had a showdown with Downing Street officials dispatched by the prime minister. That came after a positive meeting with him, she said, but did not lead to a change in attitude from others in her department.

When she was appointed by Mr Cameron last year she became one of a number of senior Jewish figures in his administration. She said she was initially optimistic, noting that officials were very supportive of her Orthodox religious requirements, from arranging "departmental cover on Shabbat, to the Jewish holidays, and providing kosher food - we are so lucky to live in a country where a government can be absolutely so completely accepting, tolerant and even welcoming".

Asked whether the culture towards the media might change under the leadership of Theresa May, she said: "I suspect it won't because it's even more important now for the government to be united."

She added: "I have never been a politician and quite frankly, I just don't want to be a politician. It's something that I found quite alien because I am a straight-talking person. I have got to get myself back together again.

"As I said to the Prime Minister, I am not going anywhere. I am still in the Lords and I am still offering to help. I can help as long as legislation goes through, to try and move it in a better direction, lead debates and ask the right questions.

"At least I can say what I think and I am not being silenced in government."