Sudanese paramilitary forces killed more than 20 people, including women and children when they attacked a village in South Kordofan, the oil-producing border state's deputy governor said Thursday.

Abdelaziz al-Hilu accused Governor Ahmed Harun, who is from a rival party and will contest local elections against him on 2 May, of "organising an attack by the Popular Defence Forces on my village, El-Faid Um Abdullah."

"They killed more than 20 people and burned between 300 - 500 houses in the early morning. Two women and four children were among those who burned inside the houses," he told AFP.

Harun, who is wanted by the International Criminal Court for war crimes in the strife-torn western Sudanese region of Darfur, was not immediately available to comment on the allegations.

The United Nations Mission in Sudan said it had sent out patrols to investigate the situation and a helicopter with UN aid agencies on board to conduct an assessment of the humanitarian needs in the area.

Wednesday's attack comes just weeks ahead of gubernatorial and state assembly elections in the sensitive northern state, in which Hilu, who heads the northern branch of south Sudan's ruling party the SPLM, is running against Harun, a stalwart of President Omar al-Bashir's National Congress Party (NCP).

Most of north Sudan's oil production comes from South Kordofan, which witnessed fierce fighting during the devastating 22-year conflict between Khartoum and the southern rebels, and where strong links to the south remain.

"Harun is trying to prevent the elections from taking place... The NCP is planning to create insecurity, and we expect worse things to happen. But we are determined to continue the campaign and to win these elections," Hilu said.

The elections in South Kordofan, due to take place during Sudan's general elections in April last year, were delayed because the SPLM strongly objected to a 2008 census, which it said grossly underestimated the state's population.

A review of the census, which resulted in the geographic constituencies being redrawn, was published in November and added more than one million people to the original count.

The Carter Centre last month criticised the voter registration process, saying the shortcomings caused a low turnout -- 100,000 voters less than for national elections in 2010 -- and lack of voter education to ensure the participation of all eligible voters.

Beyond the election uncertainties, diplomats say the return to South Kordofan and Blue Nile of troops in the southern army, as agreed under the 2005 peace accord, is a major concern, given the historic animosities and the troops' potential to destabilise a volatile area.

Hilu said that after the attack on El-Faid, two more incidents occurred on Wednesday.

"The Popular Defence Forces then went to Um Barmbita, 15 kilometres north, where they burned down all the shelters of the women who serve tea.”

"And in Um Shuran, south of Kadugli, they went to an SPLM rally and started shooting in the air and chasing the people away," he added.

SPLM officials have already accused the PDF, a militia now part of the Sudanese army, of attacking its supporters in South Kordofan's flashpoint district of Abyei, whose future status is a hotly contested issue in the run-up to southern independence in July.