Pakistani forces stormed an Indian jetliner today, ending a hijacking by Sikh nationalists who diverted a flight from India to Pakistan yesterday to press their campaign for a separate nation.

Reports indicated that the Pakistanis captured five hijackers while freeing the 60 passengers remaining aboard at Lahore Airport. A brief government announcement said there were no reported injuries in the rescue assault on the Boeing 737, which was accomplished 90 minutes before the hijackers' deadline of 10 a.m. today (1 a.m. EDT).

The hijackers had demanded a half-million-dollar ransom and the release of a radical Sikh leader from an Indian jail. The Sikhs are seeking independence for their northern Indian homeland.

The hijackers had cowed the airline crew with small daggers called kirpans that orthodox Sikh men are required to carry at all times in their unshorn hair. They freed 46 111 passengers originally aboard -- ll of them women and children except for one man with a sick wife on the plane --soon after the aircraft landed at Lahore, 20 miles west of the Indian border.

Radio Pakistan, monitored here, reported last night that more passengers, believed to be foreigners, were released later. The aircraft also carried a crew of six.

The Associated Press quoted one of the freed hostages, William Seco of Seattle, Wash., as saying one of the turbaned hijackers had cut himself in the arm with his dagger and told the hostages, "Now you know we mean business." The hijack began shortly after takeoff from New Delhi's Palam Airport when the Sikhs suddenly sprinted from the rear of the plane and overpowered the cabin crew, Seco told reporters.

"I saw a man running with four others after him," he said. "I thought they were trying to catch him but they were five hijackers rushing the cabin crew. They had knives and were holding them with the blades pointed up. At least one had a hand grenade while the others held travel bags at their sides with their hands inside as if they had bombs."

After a 15-minute struggle, the hijackers had control of the plane, Seco said.

The plane was hijacked on a domestic flight from Delhi to Srinagar, Kashmir, with a scheduled stop at the Sikh holy city of Amritsar.

Sikhs are a breakaway Hindu sect, founded around 1500, best known because of the dress of their men, who wear full beards and turbans and never cut their hair, which is wrapped around the small dagger. Indian law allows Sikh men to wear the dagger on domestic flights for religious reasons.

The hijacking is the latest and most violent episode in a running war between the government of Prime Minister Indira Gandhi and fringe groups of India's 13 million Sikhs who are demanding a separate nation, which they have named Khalistan.

Indian authorities are extremely sensitive to secessionist movements since there are a number of breakaway groups active in the country, especially in the volatile northeast, where liberation movements exist in least two states.

The authorities have reacted strongly against the Khalistan movement, which Home Minister Zail Singh, himself a Sikh, described as being pushed by outside forces. Prime Minister Gandhi has said Khalistan "exists only in the imagination of certain circles in the U.S. and Canada."

Since Sikh leader Sant (saint) Jarnail Singh Bhindranwale, 34, was arrested Sept. 20 in connection with the murder of a Hindu editor who opposed Sikh secessionism, in Punjab State in northern India, where most of this country's Sikhs live, has been rocked with sporadic violence.

There have been at least three acts of sabotage, including two attempts to derail passenger trains. Eighteen persons died in violence surrounding the Sikh extremist leader's arrest.

Pakistani President Mohammed Zia ul-Haq had assured Indian authorities that his martial-law government would do everything possible to save both the plane and its passengers.

At a hastily called press conference in Amritsar in which the extremist Sikh group Dal Khalsa claimed responsibility for the hijacking, Simban Singh Mukhpanch named five men who conducted the operation.

In Amritsar, Mukhpanch listed three major demands: the freeing of Bhindranwale; the freeing of all other jailed Sikh militants and allowing them to seek political asylum abroad and the payment of a half-million dollar ransom by Wednesday morning.