Earlier, a Pakistani air force spokesman said one violation took place in the Kashmir sector and one in the Lahore sector.

The alleged incidents come at a time of heightened tension between the nuclear-armed neighbours following the co-ordinated attacks on Mumbai two weeks ago in which more than 170 people were killed.

The Indian government has blamed the attacks on fighters based in Pakistan.

'No need for alarm'

Kamal Hyder, Al Jazeera's correspondent in Islamambad, said: "It's very difficult to believe such a thing could happen by mistake because there are defined corridors for military manoeuvres."

The incident received a great deal of coverage on Pakistani TV on Saturday.

"Tempers are running high between the two countries and such acts are likely to escalate the situation," Hyder said.

India and Pakistan have fought three wars and went to the brink of a fourth in 2002. They began a peace process in 2004, but India has said that the attacks on Mumbai put that in jeopardy.