Protesters set alight the office of Sudan President Omar al-Bashir's party in a southern town after three southern politicians were arrested in Khartoum.

喀土穆三名南部政客被逮捕，抗议者在南部某城镇向苏丹总统奥马尔·巴希尔政党办公室防火。

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Hundreds of opposition protesters gathered despite their rally being banned

There were no reports of casualties人员伤亡 at the National Congress Party (NCP) building in Wau, and police later freed the three politicians.

The SPLM苏丹人民解放运动 joined the government in 2005, ending a 22-year north-south conflict.

But tensions between the SPLM and their power-sharing partner the NCP have been rising ahead of next year's elections.

'We want freedom'

The vote will be the first presidential, parliamentary and local elections in 24 years.

Monday is the final day for voters to register for the election, and the government declared it a public holiday in an effort to企图，试图 encourage a good turnout出席人数.

But the SPLM and the NCP have failed to agree on changes to the election laws.

And about 20 opposition parties called for a gathering² in front of the parliament building in the capital to demand electoral reform.

Hundreds of demonstrators turned out, watched by lines of armed police.

The AFP news agency reported that demonstrators marched through Khartoum and its neighbouring city Omdurman waving placards and chanting: "We want our freedom."

As the protest grew - with some reports estimating thousands of people had joined the rally - police fired tear gas and beat the protesters with batons³警棍.

SPLM secretary general Pagan Amum was arrested along with his deputy Yasir Arman and Abbas Gumma, a state minister in the interior ministry⁴.

Reports said dozens of other protesters were detained拘留，扣押.

Mr Arman told a news conference that he had been beaten while in custody⁵. SPLM leaders condemned⁶ the crackdown压迫，镇压 and vowed⁷ to continue protesting.

Following the arrests, angry crowds attacked an NPC office in Wau and torched用火炬点燃 it.

Earlier reports stated that the NPC office in another southern town, Rumbek, had been burnt - but southern President Salva Kiir denied the claims.

Deteriorating⁸ relations

After the crackdown, SPLM members accused the NCP of suppressing free speech.

But interior ministry officials said the protest was outlawed失去法律保护 because the organisers had failed to apply for permission to hold the event.

Analysts¹⁰ say the argument over electoral laws and the crackdown on protesters show a deteriorating恶化 relationship between the NCP and its detractors诋毁者，贬低者.

A 22-year war between the mainly Muslim north and the Christian¹¹ and animist万物有灵论者 south claimed the lives of some 1.5 million people.

Semi-autonomous southern Sudan has been controlled by the SPLM since a peace deal in 2005 ended the civil war.

A referendum公民投票，请示书 on whether the south should secede脱离，退出 is due in 2011.