By AGENCE FRANCE-PRESSE
 
A PAZ, Bolivia, April 22 - About 20,000 demonstrators swamped downtown La Paz on Thursday to demand the resignation of Carlos Mesa just six months after nationwide protests toppled the previous president.

In addition, bus, truck and taxi drivers and street vendors held a strike across the nation, urging Mr. Mesa's ouster and protesting a gas export deal with Argentina.

The main protest was peaceful and was headed by the head of the Bolivian Labor Confederation, Jaime Solares, and the head of the driver's association, Angel Villacorta.

Mr. Mesa took office after bloody riots in October that left 80 dead and forced the president, Gonzalo Sánchez de Lozada, to resign. He fled to the United States.

How to handle the country's gas reserves - the largest in Latin America - was a major issue in his downfall, in part because he planned to export gas through Chile, with which Bolivia has a bitter century-long border dispute.

Mr. Mesa recently announced a July 18 referendum on gas export plans. But late on Wednesday, he signed a deal in Buenos Aires with the Argentine president, Néstor Kirchner, to export up to four million cubic yards of gas to Argentina for six months. Protesters said the price was below market value. The United States Embassy issued a statement reiterating "its decided support to the constitutional and democratic process" and the Mesa administration "to the end of its tenure in August 2007."