Tony Blair's authority has been dealt a fresh blow by two new Commons defeats on the government's attempts to outlaw religious hatred.

The prime minister's tenure in office was called into question just two months ago when he suffered his first defeat at the hands of MPs on plans to detain terror suspects without charge for up to 90 days.

Tuesday night's defeats will add to the pressure on ministers ahead of another expected rebellion on the government's school reform plans.

Ministers had sought to overturn two Lords amendments to the Racial and Religious Hatred Bill.

And MPs had been expected to back the government, having already passed the proposals once.

But in a sign of the government's waning authority, and the controversial nature of the proposals, MPs voted by 288 to 278, a majority of 10, in favour of keeping a Lords amendment to restrict the offence of inciting religious hatred to threatening words and behaviour rather than a wider definition also covering insults and abuse.

In a second division MPs then voted by 283 votes to 282, a majority of one, to ensure that discussion, criticism, insult, abuse and ridicule of religion, belief or religious practice would not be an offence.

Home secretary Charles Clarke, who will also be embarrassed to have again overseen proposals that have brought about a government defeat, said he would now accept the Bill as it stands.

"The government accepts the decision of the House this evening," he said.

"We are delighted the Bill is going to its royal assent and delighted we have a Bill which deals with incitement against religious hatred."

Dominic Grieve, shadow attorney general, said: ‘We are delighted with this outcome. The House of Commons has been willing to defy the government which is greatly to its credit.

"The Lords' amendments are infinitely better than the government's proposals and protect far better the right to freedom of speech."

Liberal Democrat acting home affairs spokesman Alistair Carmichael said the "strength and depth of the opposition shows just how unpopular this deeply flawed Bill was".

"Once again the Liberal Democrats have been at the forefront of opposing the unnecessary and ill-thought out legislation brought forward by this increasingly authoritarian government," he added.

Keith Porteous Wood, executive director of the National Secular Society, said the votes were "the best news on freedom of speech for decades".

"Given we had to have this Bill because it was a Labour manifesto commitment, having the Lords amendments agreed in full was more than freedom of speech campaigners dared hope for," he said.