Rebels and government forces in Sudan’s South Kordofan state have clashed again south of a railway town the insurgents briefly occupied last month.

Rebels and government forces in Sudan's South Kordofan state have clashed again south of a railway town the insurgents briefly occupied last month, both sides said on Monday.

Fighting in the state has intensified since early November, at the start of the dry season, as the government began an operation to crush the ethnic rebels who rose up two years ago.

Access to South Kordofan is restricted for journalists, aid workers and others, making verification of claims by both sides difficult.

The Justice and Equality Movement (JEM) insurgents said they had killed dozens of government troops -- including several officers -- in fighting Friday and Saturday around Abu Doma mountain, south of the rail town of Abu Zabad.

"We know the area very well," but government troops were not as familiar with the terrain, JEM spokesman Gibril Adam Bilal told Agence France Presse.

JEM occupied Abu Zabad, which is just over the border in North Kordofan state, for several hours on November 17.

JEM, originally from the western Darfur region, has been supporting Sudan People's Liberation Army-North (SPLA-N) rebels in South Kordofan since shortly after an uprising began there in 2011, analysts say.

Both groups belong to an alliance aiming to topple the Arab-dominated Khartoum regime and install a government more representative of the country's diversity.

The Sudan Armed Forces and SPLA-N are also fighting, on a smaller scale, in Sudan's Blue Nile state.

There can be no military solution to the conflicts in South Kordofan and Blue Nile, according to the United Nations Security Council.

Sudan's President Omar al-Bashir says his government is ready for a broad political dialogue, including with armed groups.