Anti-government protesters tightened their siege of Potosi on Saturday, launching a hunger strike and cutting rail links to Chile, as tourists began negotiating their way out of the mining city, 10 days into the blockade.

"We're taking this to the bitter end," said a hunger striker in the tent city that sprung up overnight in Potosi's main square.

The hunger strike includes regional officials, union and farm leaders, as well as Potosi Governor Felix Gonzalez, a former ally of leftist President Evo Morales, whom many critics charge is ignoring the plight of Bolivia's poor who voted him to power six year ago.

"This strike... is the people's answer to the lies of the government," Potosi Town Council president Remberto Gareca told AFP.

People participating in the general strike, mostly local residents, miners and farmers, want increased regional investment, including construction of a new cement factory and a larger airport.

The southern city of 16,000 people for 10 days has been cut off from the rest of the country by roadblocks made of piled-up boulders on its main access routes.

On Friday, protesters took over the city's airfield closing it to all air traffic.

On Saturday, local miners blocked the railway line to Chile, as other protesters blocked highways also leading to Chile and Argentina.

"Our rules are tough here. We don't let any vehicle through," Janet Chipana, who joined the protest from Betanzos south of here, told AFP at a roadblock.

"There are 6,000 of us. We're organised even if unfortunately we have to put up with this weather," she added as the cold wind of the Bolivian Andes whipped through the valley.

A few kilometres north of the city, around 1000 people have been stranded in San Antonio since July 29, having to alight a long column of buses stopped at a roadblock leading to Potosi.

"We're cold, hungry and afraid," Rosario Machicado told AFP, as some protesters held what they said was dynamite, threatening to blow it up should anybody try to run the gauntlet.

More than 100 tourists from several countries have been trapped in Potosi since it has been paralysed by the general strike.

On Saturday, however, around 40 tourists were able to leave the city on small planes chartered by a Bolivian tourist agency after negotiations with strike leaders, a diplomatic source told AFP, adding that more would fly out later.

Landlocked Bolivia is estimated to hold about half of the world's total reserves of lithium, a key mineral used in rechargeable batteries as well as everything from mobile phones and laptops to electric cars.