Six policemen were shot to death and four other persons were wounded by three men believed to be Sikh extremists in the Punjab city of Jullundur today.

The policemen were escorting three prisoners on trial for the murder of Ramesh Chander, former chief editor of the Hind Samachar group of newspapers published in Jullundur, who was slain in May 1984. The prisoners escaped during the attack, and the extremists fled in a waiting Jeep, taking some police weapons, the United News of India reported.

The police in Punjab have been increasingly under attack, both physically by extremists and verbally by the citizens and the state's government. Critics cite examples of police inaction in the face of extremist attacks, such as the one this morning, which took place near the police post within the district court complex.

The government of Prime Minister Rajiv Gandhi has pledged again to support the Punjab state government's efforts to curb terrorism. Internal Security Minister Arun Nehru ruled out direct central government rule or Army interference in the state, saying in Parliament this week, "We have decided to share all our information with the chief minister . . . . We are trying to provide all the assistance we can.

A commission headed by Supreme Court Judge E.S. Venkataramiah was established Wednesday to determine which Hindi-speaking villages in Punjab would be transferred to neighboring Haryana State when the city of Chandigarh is turned over to Punjab.

Chandigarh should have been transferred to Punjab on Jan. 26, under an agreement reached last July between Gandhi and Harchand Singh Longowal, the leader of the moderate Akali Party who was assassinated the following month. Chandigarh, a federally administered city, is the capital of both Punjab and Haryana , and Haryana is demanding territory from Punjab to compensate for the loss of its capital.

The commission has four weeks from April 16 to deliver its verdict, after which a three-week time limit has been set to implement its decision.

The delay in the transfer of Chandigarh to Punjab, where Sikhs are a majority and in which there is significant sentiment in favor of a state independent from India, has been an embarrassment to the state government.