Midland bishops have joined opposition to government plans to legalise gay and lesbian marriage.

But David Cameron appeared determined to stand up to pressure from church leaders and some Tory MPs, as Downing Street insisted laws allowing same-sex couples to marry would be approved before the next general election.

A statement attacking the plans has been signed by the Bishop of Coventry and of the Bishop of Hereford.

Midlands MP Jeremy Lefroy (Con Stafford) is one of a number of Conservative MPs to also oppose the proposal.

And Bishop Dr Joe Aldred, a Birmingham-based bishop in the Church of God of Prophecy and former chair of the Council of Black Led Churches, has also signed the statement.

They all join high-profile opponents of the Government’s plans including the Archbishop of Westminster, the Most Rev Vincent Nichols, who was previously the Catholic Archbishop of Birmingham, and Dr John Sentamu, the Archbishop of York, who was the Anglican Bishop of Birmingham.

But a range of Conservative MPs back plans – which have the personal support of David Cameron – to allow same-sex marriage. The Government is launching a consultation on allowing civil marriage for same-sex couples this month.

Birmingham MP Andrew Mitchell (Con), the Secretary of State for International Development, told the Birmingham Post: “The consultation is very important. It will allow us to take on board a wide range of different opinions from right across society.

“But I think that supporting loving relationships, and stable homes for children, are extremely important no matter what the sexes are of the people involved.”

The Rt Revd Christopher Cocksworth, Bishop of Coventry, and the Rt Revd Anthony Priddis, Bishop of Hereford, are among more than 100,000 people who have signed a statement opposing same-sex marriage.

It reads: “I support the legal definition of marriage which is the voluntary union for life of one man and one woman to the exclusion of all others. I oppose any attempt to redefine it.”

Bishop Joe told the Birmingham Post: “In many respects I am not a traditionalist. But in the area of the structure of the family, I am a supporter of keeping certain key principles in place and one of them is the concept that a child is best bought up in the context of a balanced family, that is with both a mother and a father.

“The bedrock of that situation is the idea of marriage between a man and a women.

“It is possible to recognise that there are other relationships that exist and to accord them the level of regard or respect that may be appropriate without tampering with the historical meaning of marriage between a man and a woman.”

With a consultation set to begin, the issue has already sparked heated debate.

Cardinal Keith O’Brien, head of the Catholic Church in Scotland, was condemned after he compared legalising same-sex marriage to bringing back slavery.

Stourbridge MP Margot James (Con), responding to the comments in a television interview, said: “I think it’s a completely unacceptable way for a prelate to talk. The Government is not trying to force the Catholic church to perform gay marriages at all. It’s a civil matter – civil marriages being introduced, that’s my understanding.”

Referring to the Cardinal’s comments again, she added: “I think this sort of scaremongering is what it is – it is just scaremongering.”

Most Rev Vincent Nichols, the leader of Catholics in England and Wales, hit out at same-sex marriages in a letter to Catholics in England and Wales which is due to be read from the pulpit in 2,500 churches during Mass.

The letter, co-signed by the Archbishop of Southwark, the Most Rev Peter Smith, reads: “We have a duty to married people today, and to those who come after us, to do all we can to ensure that the true meaning of marriage is not lost for future generations.”

It adds: “The reasons given by our government for wanting to change the definition of marriage are those of equality and discrimination.

“But our present law does not discriminate unjustly when it requires both a man and a woman for marriage. It simply recognises and protects the distinctive nature of marriage.”

Prime Minister David Cameron’s official spokesman said: “The Government has made clear its commitment to equality.

“We believe people should have the option of civil marriage, irrespective of sexual orientation.”

Legislation allowing same-sex couples to marry would come into law before the general election planned for 2015, the spokesman said.

Mr Cameron first appeared to back gay marriage in a speech in 2006 as leader of the opposition.