A rare antigovernment and antiwar demonstration, called by exiled former premier Shahpour Bakhtiar, was staged today by motorists who defied militiamen and created huge traffic jams in parts of Tehran.

Drivers jammed streets in middle-class areas despite the efforts of militiamen to keep traffic flowing on what is usually Tehran's prayer day, the quietest of the week.

No slogans were shouted or banners waved.

Vanak Square, one of the biggest junctions in the capital's prosperous northern section, was completely blocked, as were other streets and crossroads in residential areas.

Entire families occupied many of the cars. One man, out with his wife and two children, said that this action was the "only way of showing our feelings."

Bakhtiar called for the demonstration from exile in Paris, where he has lived since the 1979 Islamic revolution. He made the appeal in the name of the "national resistance" and called on the "Iranian people to demonstrate peacefully against the regime and the war with Iraq."

His message was broadcast by opposition radio stations -- mainly from Iraq -- and the appeal was also received on telex machines throughout Iran.

Bakhtiar was appointed prime minister of a last-chance government by shah Mohammad Reza Pahlavi in early January 1979, but he resigned barely a month later, after the return of Ayatollah Ruhollah Khomeini from Paris.

Although some of today's demonstrators were dressed in strict Islamic dress, others -- mainly middle-aged men -- defiantly wore western-style suits, shirts and ties.

Militiamen, armed with machine guns or revolvers, sealed off streets or directed traffic away from the main roads to try to ease the bottlenecks, while others tried to clear a way through the jams in their jeeps, sirens blaring.

There were angry confrontations between motorists and the militiamen, and several arrests were made.