KAMPALA (Reuters) - Ugandan police fought running battles with supporters of opposition leader Kizza Besigye in Kampala, in the worst outbreak of violence yet during campaigning for Thursday’s presidential election.

Uganda riot policemen pass by an injured protester during clashes in Kampala, Uganda February 15, 2016. REUTERS/Goran Tomasevic

Several people were wounded on Monday as police fired bullets and tear gas while opposition supporters hurled rocks and erected street barricades in the capital’s Wandegeya suburb, witnesses said. Hours earlier, police briefly detained Besigye.

“I have seen people shot although we’re yet to know how many exactly,” said Ingrid Turinawe, a senior official from Besigye’s Forum for Democratic Change (FDC) party.

“Many people (were) on the road bleeding, the situation is still very tense.”

Besigye is expected to be one of two main election challengers to veteran leader Yoweri Museveni, who will attempt to extend a 30-year hold on power that his opponents say has been increasingly underpinned by state intimidation and rampant corruption.

Several opposition supporters were arrested on Monday, said a Reuters photographer who also saw one person passed out in a large pool of blood, either dead or critically wounded.

Witnesses said streets were calmer in the evening but the violence has fuelled tensions before the Feb. 18 election, which Besigye and six other candidates will contest alongside Museveni.

Slideshow ( 9 images )

‘OPTIONS CURTAILED’

Besigye and Amama Mbabazi, a former prime minister and secretary general of the ruling party, have both attracted large crowds, but Museveni is expected to beat them in a poll analysts view as his toughest political challenge yet.

Earlier, Besigye was briefly detained by security services, FDC officials said, after they asked him and his supporters to use a different route for their march.

A government spokesman said all campaigning has been prohibited in Kampala’s central business district, where FDC supporters were heading.

“It’s unacceptable because it’s congested already, so Besigye had to be stopped,” Shaban Bantariza, deputy government spokesman, said.

The opposition leader has lost three previous presidential elections against Museveni and has been arrested many times, with police accusing him and his supporters of holding illegal rallies.

His supporters say such arrests are part of government intimidation tactics. They also accuse Museveni of rigging polls and using state funds to prop up his party, the National Resistance Movement (NRM). Officials deny all such claims.

Semujju Nganda, spokesman for the FDC, said Besigye had been barred from staging rallies in a Kampala stadium, and the party’s options to campaign curtailed.

“This has left us with no choice but to address voters on the streets and roads,” Nganda told Uganda’s Monitor newspaper after Besigye’s arrest.

All parties are expected to stage final rallies on Tuesday, which is a national holiday.

Museveni is credited with restoring economic and political stability after years of turmoil in the 1970s and 1980s. But unemployment, especially among the youth, has surged under his rule and critics accuse him of failing to tame corruption.