A teacher has quit after admitting he watched porn during a physics lesson with 13 and 14 year olds, even though he said it was ‘unintentional’.

Excruciating footage showed teacher Razif Nurgaliev, 62, smirking at X-rated scenes on his screen – seemingly unaware that they were also appearing on the classroom monitor in full view of the students.

The teacher, who had worked at the school for almost 40 years, gawped at the pornography after setting work for his co-ed class in Tashkinovo village, near the Russian city of Neftekamsk.

He had forgotten his laptop was connected to the electronic blackboard, it was reported.

A pupil filmed the shocking series of events from behind his physics textbook.

Initially a school source tried to blame the teenagers for playing a prank on the veteran teacher.

But the teacher admitted to education officials: ‘I clicked on something, and some website opened.’

He had been trying to open an online journal, and had not intended to watch the explicit material, he said.