British Prime Minister Gordon Brown has confirmed that a senior member of his cabinet, Transport Secretary Ruth Kelly, is to step down.

There had been speculation that Ms Kelly, who was born in Limavady in Co Derry, might leave the cabinet over her objections to the Human Fertilisation and Embryology Bill.

The bill is intended to regularise the use of embryos in scientific research.

Earlier this year, Ms Kelly, who represents Bolton West, and two other Catholic cabinet ministers voted in favour of an unsuccessful attempt to ban the use of hybrid human-animal embryos.

Ms Kelly, who has previously drawn criticism from some quarters for her links to the Catholic group Opus Dei, will remain in her post for the time being.

She had been an ally of the prime minister but the timing of her departure could overshadow his latest efforts to rally the Labour Party behind him.

In a speech to Labour's annual conference yesterday, Mr Brown defied calls for him to go, saying he would stand by his beliefs and fight on to make life better for people living in Britain.

The former finance minister said that with global markets in crisis this was no time for a novice, a remark aimed at the opposition Conservatives and perhaps potential Labour rival David Miliband.

After 11 years in power, Labour is some 20 points behind the Conservatives in opinion polls, putting the government on course for a crushing defeat at the next election - due by mid-2010.

Ms Kelly, 40, became the youngest minister in the cabinet when she entered the top echelons of government at the age of 36 after a series of swift promotions through the ranks.

Since then she has held three cabinet posts - heading the departments of Education and Skills, Communities and Local Government, and finally Transport.