Displaying a rare courtesy, Prime Minister Manmohan Singh [Images] Thursday apologised to prominent Pakistani human rights activist Asma Jehangir whose hotel room in New Delhi was searched by police without any warrant.

Singh, who knows Jehangir, spoke to her and personally apologised for any inconvenience caused to her, prime minister's media adviser Sanjaya Baru said.

It was explained that there was heightened security at the moment and police were on high alert.

Jehangir, who is part of a Pakistani delegation to discuss human rights violations in South Asian countries, said she had checked into a hotel in Sundar Nagar in South Delhi on Monday.

Shortly thereafter, police had "barged" into their rooms and started going through their luggage and other belongings, she said.

When contacted, DCP (South) Anil Shukla said ahead of Independence Day, it was "routine checking" conducted in hotels and restaurants.

He said the hotel owner had informed that some foreigners were staying in his hotel. No inconvenience was caused to them, he said.

City Police Commissioner K K Paul has ordered the probe into the "circumstances and nuances" of the entire episode, spokesperson of the Delhi Police Deependra Pathak told PTI. The probe will be conducted either by vigilance or a senior official of the rank of joint commissioner, he added.