In a free vote on Monday, MPs voted in favour of giving a Commons second reading to the Sexual Offences (Amendment) Bill by 313 to 130.

The BBC's Jon Devitt: "Fundamental objections from opponents"

The Bill proposes to lower the age of consent for homosexuals from 18 to 16, the same age as for heterosexuals.

But Baroness Young, who led last summer's successful attempt to preserve the status quo, said: "My personal view has not altered - I'm opposed to the lowering of the age of consent."

When asked if she expects a fresh confrontation with the Commons over the Bill she said: "Yes that's right." But she added she would have to see the precise form of the Bill and gauge support from her fellow peers.

But even if peers oppose the Bill the government can force it through the Lords by using the Parliament Act.

Earlier, Home Secretary Jack Straw opened the debate by telling MPs: "This is not a question of encouraging one lifestyle or another or encouraging young people to have sex - far from it.

"It is instead a question of equality before the law. It is not in my personal view right for the law to discriminate against those who are homosexual."

Mr Straw stressed that the decision to couple the vote with another on a proposal to create a new offence of abuse of trust was intended to meet concerns raised when the issue was discussed previously.

Jack Straw addresses the House of Commons

The new Sexual Offences (Amendment) Bill will introduce a 16 age limit in England, Scotland and Wales, and 17 in Northern Ireland if it becomes law.

The Lords blocked a cahnge in the law in 1998

The government's move to equalise the age of consent follows a European Court of Human Rights ruling that British law contravened the European Convention on Human Rights.

The bill will simultaneously create an offence of "abuse of trust" to protect vulnerable 16 and 17-year-olds who might be at risk from those who could influence them, such as teachers.

The offence will apply to those aged 18 or over who either have sex with, or engage in other sexual activity with, a person younger than them when they hold a position of trust.

The BBC's Christine Stewart: MPs will vote with their conscience, not along party lines

Tory Desmond Swayne (New Forest W) said the law should restrain activity that the majority viewed as "undesirable or unnatural".

But Mr Straw said there was no evidence that when homosexual acts were illegal at any age, this cut the number of people engaging in them.

Instead, it led to "huge human unhappiness and very great injustice".

Mr Straw admitted that drawing a line on abuse of trust had not been easy but reckoned the government had got it about right.

Shadow Home Secretary Sir Norman Fowler welcomed the move to protect children in care but said he would oppose any lowering of the age of consent for gay sex.

However strongly MPs felt on the issue, they "would do well to take note" of public opinion which felt there was a responsibility on adults to "do everything in our power" to avert the risk of children being abused.

Sir Norman warned, that risk "could be or would be made worse by lowering the age of consent".

'Law cannot be justified'

Alan Beith, Liberal Democrat deputy leader, said: "My view is that the present discriminatory law cannot be justified from any ... standpoints and that it has some harmful consequences.

"Moral disapproval on the part of some people, however strongly held, doesn't provide grounds for making private acts into criminal offences.

But Democratic Unionist Party Leader the Rev Ian Paisley, who earlier led a delegation of churchmen to hand in a 18,000-name petition to Downing Street protesting at the Bill, said the UK should not follow the rest of Europe down the road of lowering the age of consent.

Labour's David Borrow, who told MPs he had come to the conclusion he was gay during the sixth form and at university, insisted homosexuals should be equal under the law with heterosexuals.