MOSCOW--President Mikhail S. Gorbachev said yesterday the strikes in Soviet coalfields were the biggest test of his four-year economic reform plan, and he called for a shake-up of the local councils which are often blamed for stopping progress.

Gorbachev had appealed last week for a "renewal" of Communist Party ranks from top to bottom, and his suggestion that local governing bodies also be transformed could mean sweeping leadership changes.

Local elections scheduled in the spring throughout the Soviet Union involve multiple candidates and for the first time offer serious challenges to entrenched officials.

Speaking to the national legislature, the Supreme Soviet, Gorbachev said party and government bodies as well as official trade unions should meet immediately to analyze the two-week strike that at its peak idled half the Soviet Union's one million workers in the coal industry and deprived vital factories of fuel.

The Kremlin chief told legislators almost all the miners have now returned to work.

"We are coming out of a very serious crisis, the biggest test during the four years of perestroika," Gorbachev said.

He said the test was even more severe than the April 1986 explosion and fire at the Chernobyl nuclear power plant that killed 31 people, cost millions of dollars to clean up and sparked a nationwide environmental protection movement.

The strikes dealt a serious blow to the economy, Gorbachev said, but he reassured his fellow Soviets that "our perestroika will give results despite the tests we are undergoing."

He blamed coal ministry and local officials rather than the miners, but warned "deciding such questions by striking will ruin our work."

In Washington, White House spokesperson Marlin Fitzwater declined comment on the Soviet strikes and violence between ethnic groups in some Soviet republics.

"We don't think it's appropriate to get involved in trying to tell them how to conduct their internal problems and issues," Fitzwater said.

Communist maverick Boris N. Yeltsin told the Supreme Soviet that local party and government leaders have been inactive and insensitive to people's needs because "they know they won't be re-elected."

Gorbachev said that because of the strike, governing councils should not wait for elections to make changes.

"Ripe questions require sessions without delay to discuss reports of regional executive committees, and where it is necessary to take personnel decisions, they must be taken without waiting for elections," he said.

Several heads have already rolled, Tass official news agency reported. It said the party chief and mayor of Stakhonov in the Donetsk basin "were forced to leave their posts," apparently under pressure from strikers.

One legislator suggested strike committees be absorbed into local governing councils because they have proven they can get things done.

In a meeting last Tuesday with party officials, Gorbachev said the party also needs a "flow of fresh blood, and...to be renewed at the level of the work place, the locality, the city, the region, the republic, the central committee, and the Politburo."