Volent clashes between students and police in several cities over the past week have been caused by long-simmering student opposition to martial law, press censorhip, and the strict ban on political activity.

The protest marches, police stonings, burning of vehicles, and barricading of streets may have been sparked by the formation this month of a joint front of political parties pledged to bring and end to the 3 1/2-year-old military government. A catalyzing factor was a new ordinance giving the government complete control over the staffing of colleges and universities. Teachers opposing the ordinance were said to have incited the students to violence.

Left-wing student organizations have given their full support to the nine-party Movement for the Restoration of Democracy formed on Feb. 7. Gen. Mohammed Zai ul-Haq's government has already curtailed it's activities be detaining three leading members and "expelling" other from Karachi to their home towns. The strongest alliance member, the Karachie-based Pakistan People's Party, may be relying on student supporters to mobilize public opinion against Zia's rule.

People's Party leaders, former prime minister Zulfiqar Ali Bhutto's widow, Nusrat, and Daughter, Benazir, are known to be devoting much time to their student wing, the Pakistan Students Federation. The apparently well-financed federation swept the polls at the 1980-81 winter student union election, a significant development in student politics that has been dominated for years by the elitist Islamic fundamentalist Jamaat-i-Islami.

"Jamaat students bring in weapons and ammunition to terrorize progressive students and break up their meetings," said a student leader in one of the remaining predominatly Jamaat universities. "If a student objects, Jamaat members known as the 'thunder squad' beat him up and destroy his belongings. The police often refuse to get involved. If they do, the thunder squad usually gets treated leniently."

Last December, one youth was killed and several injured in fighting between rival political groups in four colleges. Armed Jamaat student still roam around these colleges.

Many students believe the Jamaat support the military government in return for its backing. They accuse the military of protecting, even licensing crime. Others maintain that the government fears the right-wing Islamic Party as much as the students.

In the student elections last December, progressive student leaders beat Jamaat contenders to 50 out of 54 student union seats in the North-West Frontier Province, 10 out of 12 in the capital Islamabad and its twinc city of Rawalpindi, and more than half in the province of Punjab. Student elections have not been held in Sind or Baluchistan.

The victory has united students supporting the Pakistan People's Party, the centrist Tehrik-i-Istiqlal Party, and liberals calling themselves "Pioneers" and "eagles."

"We are against martial law and press censorship; we believe Pakistian must have elections and a political process," said a progressive student leader from Rawalpindi's Gordon College, which has always been in the forefront of any antigovernment activity. Last Weekend Gordon College organized a protest march by three Rawalpindi colleges that results in the arrest of 20 youths.

"We are hopeful of the new political party alliance," said the student leader, "if the politicians come out in to the streets, the students and lawyers will follow."

The military's treatment of the student disturbances last week, however, illustrates the problems Zia's political opponents may have to face.

In most cases the demonstrations were halted within three hours by riot police with tear gas and steel-tipped batons. Students were arrested. Colleges and universities were closed until further notice.

A similar crackdown occurred in Karachi six weeks ago, just before a planned student debate and "bazaar" to celebrate the birth date of Bhutto. Colleges were surrounded by police and about 50 persons were picked up. They have been charged under the martial law act of plotting anti-government activity and are still in jail.

Among their number were students and journalists allegedly involved in the production of opposition pamphlets and papers printed clandestinely in Persion Gulf states and smuggled over the Baluchistan border.

"We cannot meet or even express our feelings," said one frustrated student leader from Islamabad this week. "After a demonstration students are picked up overnight. If we try to speak we find ourselves behind bars or beaten up."

He warned that student tension was bilding and changes were coming. But whether the students and their political backers have the strength to overcome martial law is questionable.