The Centre has issued an advisory to all states and Union territories, asking them to intensify surveillance as terrorist groups might target Air India flight connecting Kabul and Indian naval facilities on or around Independence Day.

The government has tightened security as the execution of 1993 Mumbai blasts convict Yakub Memon has prompted greater terror threat to India. The recent Gurdaspur terror attack also called for the heightened security arrangements.

In the seven-page advisory, the Centre has warned of possible hijacking or bomb blast on a Delhi-Kabul flight of Air India by Lashker-e-Taiba (LeT). The advisory also mentions that al-Qaeda is planning to target Indian naval facilities, including the Karwar naval base (INS Kadamba), the Southern Naval Command in Kochi (INS Venduruthy) and the Mumbai-based Western Naval Command, The Times of India reported.

The intelligence agencies suspect that the plan to hijack the Air India flight has been engineered by Pakistan's Inter-Services Intelligence (ISI).

"Independence Day function ... provides an attractive target for various militant, terrorist outfits ... and rabid communal elements due to high publicity value and concentrated presence of dignitaries," the advisory said.

The advisory, issued on 7 August, says that al-Qaeda's list of probable tergets also includes BJP offices, commercial, aviation, tourist and railway facilities. The terror outfit might also target food joints, cafeteria and other places frequented by foreign nationals and therefore, the Centre has asked for deployment of specially trained "watchers", who will keep a vigil on these places.

Earlier, the Ministry of Home Affairs had also issued warnings of possible terror attacks on important installations in the country by various terror outfits, including Indian Mujahideen (IM), Jaish-e-Mohammed (JeM), Tahrik-e-Furqan (TeF), Lashkar-e-Taiba (LeT) and Pasban-e-Ahle Hadis (PAH).

Elaborate security arrangements have been made in the national capital ahead of the 69th Independence Day celebrations in view of the increased threat perception. The Red Fort, where Prime Minister Narendra Modi will hoist the tricolour on 15 August 2015, has been put under high surveillance too.

Modi, who is said to be at a greater risk than any other leader this year, will be given bullet-resistant glass shield on the stage. Last year, he had addressed the gathering without this protection.