Pakistan said on Saturday that Indian warplanes had violated its airspace but said this was "inadvertent" and there was no cause for alarm about an escalation of tension between the nuclear-armed neighbors. An Indian Defense Ministry spokesman said he had no information on the reported incursion. The Times of India quoted Indian Air Force sources as saying there had been no such incident. A Pakistan Air Force spokesman said there were two violations, one in the Kashmir area and another in the sector around the city of Lahore in Pakistan's Punjab province. The report followed a rise in tensions between the nuclear-armed neighbors after gunmen killed 179 people in India's financial capital Mumbai in an attack which New Delhi blamed on Pakistan-based Islamist militants. "We have confirmed it," Pakistan Information Minister Sherry Rehman said. "We have spoken to the Indian Air Force and they have said it was inadvertent." "Our Air Force is on alert and ready to face any eventuality, but we do not expect this to escalate," Rehman said. "There is no need for alarm." The Times of India website quoted "highly placed sources" in the Indian Air Force as denying any such incident. India has been extremely careful in recent years to prevent its warplanes from straying into Pakistan's airspace. Pakistan shot down two Indian planes which it said had gone into its airspace during the 1999 Kargil conflict, fought on the Line of Control dividing disputed Kashmir. India said the planes were in its airspace when they were shot down. Following the Mumbai attacks, India, backed up by the United States, has called on Pakistan to crack down on Pakistan-based militant groups. But the government has resisted domestic pressure to launch retaliatory strikes of its own. India has accused the Lashkar-e-Taiba (LeT), a militant group it says was set up by Pakistan to fight Indian rule in Kashmir, of involvement in the Mumbai attacks. LeT and a charity linked to the group are both strongly represented in areas around Lahore and in Kashmir. Pakistan has rounded up some of the 40 people India has demanded should be extradited for the Mumbai killings, but says that India has not provided any evidence of links to the attacks. According to a newspaper report last week, Pakistan put its forces on high alert during the Mumbai attacks after someone pretending to be India's foreign minister made a phone call to President Asif Ali Zardari threatening war.