FOUR schoolboys have been barred from using the Internet after they logged on to a porn site during a science lesson.

Hugh Porter, headteacher at Joseph Rowntree School, in New Earswick, York, said all pupils had been warned action would be taken if the rules were broken.

But one of the boys' mothers said the school's system should have the ability to filter out such sites.

One mother said her 12-year-old son and three other boys had looked at the porn site when they were supposed to be using a computer as part of a science lesson.

"I didn't know my child could get on to something like that. I thought there was a block on it," she said.

"It's quite frightening that they can get quite easy access to this sort of material. I don't think my son is mature enough when there's a group of boys egging each other on."

Mr Porter said the school's policy was that students under the age of 16 were not allowed access to the Internet on school computers unless they were with a teacher or under the supervision of a sixth former in after-school activities.

They had been told that anyone accessing "inappropriate sites" would be banned from using the Internet and pupils and parents had signed letters setting out this policy.

He added that a filter system may have to be introduced.