|Nikolic said he was hunger-striking in an effort to force early elections in Serbia [Reuters]
Serbia's leading opposition politician has been admitted to hospital a day after announcing a hunger strike in an effort to force early parliamentary elections.
Tomislav Nikolic, leader of the nationalist Progressive Party, was taken to a Belgrade clinic after collapsing late on Sunday after refusing food and liquids. His deputy, Aleksandar Vucic, told reporters Nikolic was "in pain and convulsing".
A doctor at the clinic told the Reuters news agency that Nikolic was "in a serious condition with high blood pressure" and refusing therapy.
Earlier on Sunday, Nikolic was visited in his parliamentary office by Boris Tadic, Serbia's pro-European president, who asked him to end his hunger strike.
Tadic said he would not call elections until Serbia was granted candidate status for European Union membership later this year.
"We have a chance we've never had before," Tadic said of Serbia's bid for EU membership. "That will be a crossroads for our country."
Nikolic and his party's supporters blame Tadic for the Balkan country's economic troubles and claim his pro-Western policies are damaging Serbia. The party are expected to stage "massive protests" in Belgrade from Monday.
Addressing some 50,000 supporters at a rally on Saturday night, Nikolic said he was no longer taking food or water. On Sunday morning he told reporters he was prepared to "go to the end".
"This is not just about early elections, it is about the overall situation in Serbia," Nikolic said. "Whatever the outcome, no one will be able to ignore my move."
Nikolic was narrowly defeated by Tadic in the last presidential election in 2007. Tadic's Democratic Party consolidated their grip on power later that year by winning parliamentary elections as well.