BUCHAREST, ROMANIA, DEC. 15 -- Romania's main opposition parties created a broad coalition today to oppose the ruling National Salvation Front amid a swell of anti-government protests by workers and students.

The six largest parliamentary opposition parties joined to form the National Convention for the Introduction of Democracy.

One of them, the National Liberal Party, said it had pressed President Ion Iliescu to remove Prime Minister Petre Roman's government for bungling market economic reforms, and asked the president to form a coalition.

Strikes and protests multiplied with the approach of the first anniversary of the December 1989 revolution in which Communist dictator Nicolae Ceausescu was toppled and executed.

In the western city of Timisoara, where an uprising last Dec. 16 ignited the revolt, at least 5,000 workers and students rallied in the snow today to demand the resignations of Iliescu and Roman.

About 50,000 students continued sit-in strikes at colleges across the country. The Interior Ministry announced it was ready to protect public buildings and people inside them because "the possibility of political violence exists."

Today's protest in Timisoara supported a strike there by students and workers that has shut down most factories and colleges in the city this week. Across the country, drivers, teachers, nurses, doctors and other workers have joined strikes.

Trade union leaders and the Civic Alliance non-parliamentary opposition movement had hoped to bring the government down with a general strike similar to that which toppled the Communist-led government in Bulgaria this month.

The Civic Alliance said it had accepted an offer of talks with Iliescu and canceled a series of anniversary rallies over the next week because it feared bloodshed. "We made this decision because we know irresponsible and criminal individuals are ready to turn any street movement into a bloodbath," alliance leader Marian Munteanu said.

But another group of opposition parties said members would demonstrate Sunday outside the former Communist Party headquarters on Bucharest's Revolution Square.

The Rev. Laszlo Tokes, whose persecution by Ceausescu's secret police touched off the Timisoara uprising, said he had organized an international ecumenical conference in the city Sunday to commemorate the revolution and to promote national conciliation.