La Paz – A student was killed in Bolivian protests on Wednesday amid increasing pressure on President Evo Morales to resign over opposition claims that he rigged his recent re-election.The 20-year-old student died of injuries sustained in clashes between pro- and anti-government demonstrators in the central city of Cochabamba, a doctor at the local hospital told AFP. Some 20 other people were wounded in the fighting, some seriously, ombudsman Nadia Cruz said.The fatality brings to three the death toll in clashes following the controversial October 20 election that saw Morales, 60, win re-election in a first round of voting – but only after a pause and an abrupt shift in the vote count in his favour, which his opponents have branded as fraudulent.Morales, first elected president in 2006, is seeking to remain in power until 2025 after he took legal action to get around constitutional term limits. He tweeted "deep regret" over the death on Wednesday, and described the student as "an innocent victim of violence promoted by political groups that encourage racial hatred among Bolivian brothers".Meanwhile Luis Fernando Camacho, an opposition leader based in the Santa Cruz region, flew to La Paz where he was joined by ex-president Jorge Quiroga (2001-2002) and opposition politician Gustavo Pedraza, with plans to deliver a letter to the president demanding his resignation.The powerful Catholic Church cautioned against such an open challenge to Morales' authority."Asking for the president's resignation is a radical measure," said Sucre Archbishop Jesus Juarez.Homemade bazookasThe Cochabamba clashes took place after members of farmers' unions, mainly women, began an effort early in the day to clear opposition roadblocks that have stopped traffic for several days.Rival groups fought pitched battles in the city with rocks and sticks. Some protesters launched firecrackers from homemade bazookas. The town hall in neighbouring Vinto, a stronghold of Morales' ruling MAS party, was burned down."Evo, friend, the people are with you!" supporters chanted before clashing with opponents, mainly students, in a city square.Anti-Morales protests were also held on Wednesday in the cities of Santa Cruz, Sucre, Tarija and Potosi, shutting down state offices and companies.Bolivia's state oil company warned of likely fuel shortages because of the protests. "It is impossible to supply service stations," it said in a statement.Conservative leaderConservative opposition leader Camacho, 40, has called on military support to oust Morales from office.Morales, speaking at a naval ceremony on Wednesday, insisted that the military must "serve the people" and support his government.Up to now Bolivia's armed forces have stayed neutral in the electoral dispute – and calling on the military to solve political problems is a highly controversial move.Bolivia saw numerous military uprisings and dictatorships during its republican life before civilian rule was established in 1982.Carlos Mesa, who ran second against Morales in the October polls, has called for a new vote to be held.