A planeload of illegal immigrants landed in Pakistan from Spain yesterday, but officials found that most of the passengers were from Indian Kashmir and planned to send them back to Spain.

Pakistan's embassy in Spain issued "emergency passports" to 42 illegal immigrants but informed immigration officials in Pakistan that it was unsure about their nationalities.

"To the surprise of our staff, there was only one Pakistani among them," said Tariq Pervez, head of the Federal Investigation Agency, which deals with immigration.

He said most of the passengers were from Indian Kashmir. "We are interrogating them and will send the non-Pakistanis back to Spain," Mr Pervez said.

Kashmir is regarded as the core dispute between India and Pakistan, and the divided Himalayan region was the cause of two of the three wars between them since independence from British colonial rule in 1947.

A cross-border bus service launched last year is the most tangible result from a peace process begun by Pakistan and India nearly three years ago.