Barry Sheerman (Huddersfield), Children, Schools and Families Select Committee chairman, said he had been told recently of the "disgusting" behaviour seen by teachers in infant schools.

And he launched a blistering attack on Rupert Murdoch's media empire, which he said was the biggest carrier of pornography in the world.

A company that made available such "filth" that could be seen by children did not impress him, he said.

Mr Sheerman's comments came during Commons debate on the Queen's Speech when he complained that Britain was "awash" with focus on early sexual activity.

He had been angered to read that Mr Murdoch and his son James Murdoch, chief executive of News Corporation in Europe and Asia, wanted to see BSkyB become more trusted than the BBC.

Mr Sheerman told MPs: "We are a country awash with focus on early sexual activity."

He said the amount of pornography on the internet and satellite television that was available to children "disturbed" him.

Mr Sheerman added: "I think it is very serious the access to pornography to children ... you go to infant schools now and teachers say to me: 'Children come here at five and six simulating sexual behaviour that they should know nothing about.' "That is something pretty disgusting.

"I was angered the other day when I read that Rupert and James Murdoch wanted to turn BSkyB into a more trusted and more loved broadcaster than the BBC.

"I had only read two days previously that not only is the Murdoch empire the biggest carrier of pornography in the world but have now bought a major supplier, maker of pornography in the US.

"I don't know what trusted and loved is but a company that puts that sort of filth, makes it available to children, does not impress me.

"Our children should be protected from that sort of pornography whether it is on BSkyB or whether it is on the internet.

"I believe that childhood ought to be protected."