India said today it had arrested four Kashmiri separatists in connection with the hijacking of an Indian airliner, and it accused Pakistan of masterminding the eight-day drama.

"Those on the trail of the wrongdoers have been able to make a significant breakthrough," said Home Minister L.K. Advani. "Pakistan is neck-deep in this dirty game of hijacking."

Pakistan denied it was involved in the hijacking, which began on a flight from Katmandu, Nepal, and ended in Afghanistan on Dec. 31 after India agreed to free three Kashmiri activists from jails in Kashmir in exchange for the 155 hostages. One passenger was stabbed to death.

Kashmir is a majority-Muslim region claimed by both Pakistan, which is mostly Muslim, and India, which is mostly Hindu.

Advani said four members of Harkat ul-Mujaheddin, a Pakistan-based guerrilla group fighting for Kashmiri independence, were arrested in Bombay on suspicion of providing support for the hijack plan two months before it was launched.

Two of the four were Pakistanis and one was a Nepali. The fourth was an Indian who, Advani said, was recruited by Pakistan's secret service and later underwent intensive guerrilla training at camps in Pakistan and Afghanistan.

"Interrogations [of those arrested] have confirmed that all five [of the hijackers] are Pakistanis, that this was a Pakistani operation," Advani said.

Islamabad said India could be fabricating evidence. "There is no evidence," Pakistani government spokesman Tariq Altaf said of the allegations. "Where is the evidence?"

Pakistan has said it does not know the identities of the hijackers and has vowed to arrest them if they enter the country. "Only India knows their identity," Altaf said.

A spokesman for Harkat ul-Mujaheddin called the Indian assertions "a pack of lies." Earlier, Javed Jabbar, adviser to Pakistan's military ruler Gen. Pervez Musharraf, told the BBC that there "will be manipulation and fabrication" of evidence.

"There was no involvement whatsoever of the government of Pakistan in any aspect of the incident. Absolutely not," he said.

Advani identified the hijackers as Ibrahim Athar from the Pakistani city of Bahawalpur, Shahid Akhtar Sayed, Sunny Ahmed Qazi and Mistri Zahoor Ibrahim from Karachi and Shaqir from Sukkur city.

India accuses Pakistan of fomenting a separatist insurgency in Kashmir, over which the rivals have fought two of their three wars. Pakistan says it provides only moral and diplomatic support to the Kashmiri people's struggle for self-determination.

Maulana Masood Azhar, leader of Harkat ul-Mujaheddin and one of the three Kashmiri activists freed, spoke Wednesday before about 10,000 supporters in Karachi. He said today in an interview with the Associated Press that the hijackers identified themselves as Indian nationals and declined to remove their masks even in the presence of the men whose freedom they had negotiated.

The group--hijackers and freed prisoners--traveled together for 25 minutes, heading toward Pakistan. At a desolate spot, the hijackers ordered the vehicle stopped, got into another vehicle and left.

"They said, 'We are returning to India, but we can't travel with you. We will get there another way,' " Azhar said.