A sword-wielding man described as "insane" killed two Sudanese soldiers on Saturday before being shot dead as he tried to enter the palace where President Omar al-Bashir has his offices.

The attacker refused to stop at the presidential palace's western gate before seizing a gun from one of the guards, killing two of them and being shot dead himself, presidential press secretary Emad Sidahmed told Agence France-Presse.

Sudanese troops have denied peacekeepers access to a Darfur town when they tried to investigate media reports of a "mass rape" attack, the United Nations said on Wednesday.

A patrol from the U.N.-African Union Mission (UNAMID) traveled Tuesday to Tabit, 45 kilometers (27 miles) from the North Darfur state capital El Fasher, where local media had reported the "mass rape" of 200 women and girls.

Britain, France and the United States are demanding that action be taken against senior officials from the U.N. mission in Sudan's Darfur who failed to report crimes by Sudanese forces, diplomats said Wednesday.

An internal U.N. probe of allegations that the U.N.-African Union UNAMID mission in Darfur was covering up crimes by Sudanese forces against civilians found that there was an under-reporting of crimes.

After months of threatening to impose sanctions on South Sudan leaders, the U.N. Security Council is ready to take action to punish those responsible for violence in the country, the council president said Tuesday.

The 15-member council had until now held off on sanctions to allow peace efforts by African regional leaders to yield results.

The presidents of Sudan and South Sudan agreed Tuesday to resume work to demarcate their contested border, a dispute that boiled over into armed conflict between the countries in 2012.

The south split from the north in 2011 under a peace agreement ending 22 years of civil war, and the two remain at odds over unresolved issues from the secession, including the frontier.

An opposition leader said intelligence agents barred him from leaving Sudan on Sunday, weeks after he was released from jail following his criticism of security services.

Sudanese Congress head Ibrahim al-Sheikh said he passed customs at Khartoum airport when a National Intelligence and Security Service (NISS) officer prevented him from boarding his flight to Dubai.

Libya's internationally recognized Prime Minister Abdullah al-Thani said Wednesday he was ready to talk to militias who control most of his country if "all sides" made concessions.

Thani's government took refuge in the remote eastern town of of Tobruk in August after Islamist-led militia seized the capital Tripoli and then set up a rival administration.

Sudanese security forces arrested a journalist for the London-based Arabic-language newspaper Al-Hayat in Khartoum Thursday, his family said, unaware of the reasons for his detention.

Agents from the National Intelligence and Security Services (NISS) arrested Al-Nur Ahmad al-Nur, a Sudanese reporter for Al-Hayat, at around 6:00 pm (1500 GMT) on the central Mek Nimir street.

Sudanese President Omar al-Bashir -- in power since a 1989 coup -- will stand for re-election in 2015 after being retained Tuesday as leader of the ruling National Congress Party, a top aide said.

Bashir, the only sitting head of state wanted by the International Criminal Court (ICC), was re-elected as both leader and presidential candidate of the NCP at a party convention, said his chief assistant, Ibrahim Ghandour.

Sudan's ruling party Monday named President Omar al-Bashir as a possible candidate for the country's April presidential elections, an adviser said, despite doubts he would stand again.

After taking power in an Islamist-backed coup in 1989, it had been unclear in recent years whether Bashir would run again in next year's polls.