The new Bolivian military government announced today that it 'has signed a truce with insurgent mineworkers, virtually ending the last serious internal opposition to the junta led by Gen. Luis Garcia Meza.

Meanwhile, the military government banned the activities of most trade unions and professional organizations, in effect outlawing the once-influential Central Labor Organization.

The junta said 9,000 to 10,000 tin miners reported back to work yesterday in the rugged, southeastern section of Bolivia that was the center of armed resistance to the new leadership.

The armed forces took over from interim president Lidia Gueiler Tijaoa in a coup July 17. Diplomatic sources said Gueiler, who took asylum at the Vatican's mission here, would probably go to France to live in exile.

[In Washington, Secretary of State Edmund Muskie announced that the United States had halted all economic aid to Bolivia except for foodstuffs and humanitarian aid. He also said the U.S. Embassy staff would be reduced and U.S. military advisers withdrawn. Washington recalled U.S. Ambassador Marvin Weissman and terminated all military assistance to Bolivia shortly after the coup.]

Bolivia's militant miners have a tradition of resisting right-wing military rule, usually with tragic results.

The 50,000 miners, who produce the tin, copper and other minerals that bring in about 70 percent of Bolivia's foreign exchange, adopted a defiant stand when the armed forces overthrew the government last week.

They said over a radio network they controlled that they were waiting, armed with dynamite, for any attack by soldiers surrounding the mining district.

The miners, however, said Army troops were cutting off their food supplies in an attempt to starve them into submission. The tactic appeared to undermine the miners' resistance, and sources close to the miners cited the food cutoff as the reason the miners returned to their jobs.

The partial end of the strike could not be confirmed by union leaders, many of whom are in hiding or reportedly have been arrested by the armed forces. Other reports suggested that pockets of resistance remained.

The state railway company said today that two railroad bridges had been dynamited in southern Bolvia, interrupting freight and passenger service to Chile. Airlines were operating on schedule.

In general, other parts of the country appeared to be returning to normal. Many factory workers in La Paz were back on the job after heeding a call for a general strike earlier in the week. Transportation and commerce in La Paz were operating again.