More than 3,000 people were killed in South Sudan in brutal massacres last week in bloody ethnic violence that forced thousands to flee, the top local official in the affected area said Friday.

"There have been mass killings, a massacre," said Joshua Konyi, commissioner for Pibor county in Jonglei state.

The United Nations has reinforced its peacekeepers in the flashpoint South Sudan town of Pibor and is airlifting food to the region, where tribal violence has prompted thousands to flee, a senior U.N. official said Saturday.

"We have deployed a battalion-sized force in Pibor to support the government to protect civilians," Lise Grande, the U.N. humanitarian coordinator for South Sudan, told Agence France Presse, adding that the provision of food aid was an "urgent step.”

All six crewmen aboard a Sudanese military helicopter were killed when it crash-landed and burned in North Kordofan state on Friday, the army said.

Fire broke out because of a "technical problem" aboard the Russian-made aircraft three minutes after takeoff from a base at El Obeid, the state capital, army spokesman Sawarmi Khaled Saad told Agence France Presse.

Gaza's Hamas premier Ismail Haniya held talks with Sudanese President Omar al-Bashir Thursday on his first official regional tour since the Islamists' 2007 power seizure in the Palestinian enclave.

Haniya, who arrived in Khartoum on Tuesday, was joined in the meeting by other high-ranking Hamas leaders -- the first time they had met as a group with Bashir, whose country has close ties with Hamas.

Sudanese air raids killed 17 people in the South Sudan border state of Western Bahr al-Ghazal on Thursday, the second day of stepped-up bombing along the northern frontier, Juba's military spokesman said.

Khartoum dismissed the allegations as "incorrect."

Hamas Prime Minister Ismail Haniya will begin a tour on Sunday, his office said, his first exit from Gaza since Israel and Egypt imposed a siege in 2007.

Sources in his office told AFP that Haniya would visit Egypt and Sudan, after which he plans to go to Qatar, Turkey, Tunisia, and Bahrain.

Sudan's army killed a key rebel leader from the Darfur region Sunday, state media reported, three days after anti-government forces said they had begun advancing on the capital Khartoum.

"The Sudanese army announced that they killed Khalil Ibrahim in fighting today in west Wadbanda, North Kordofan," the official Sudan News Agency (SUNA) said.

A veteran Sudanese military intelligence officer was heading to Cairo on Thursday for preparatory meetings to lead an Arab League observer mission aiming to end nine months of violence in Syria.

General Mohammed Ahmed Mustafa al-Dabi was named on Tuesday to head the team, a day after Syrian President Bashar Assad's embattled regime agreed after weeks of stalling to accept the observers.

South Sudanese rebel chief George Athor has been killed in a clash with soldiers of the newly independent nation, Vice President Riek Machar said on Tuesday.

One month after vowing to continue his battle against the Juba government, Athor died when a South Sudanese border patrol clashed with "elements" with him in Morobo County at about 1500 GMT on Monday, Machar said.

Heavy fighting between the Sudanese army and southern-aligned rebels in the embattled state of South Kordofan has killed at least 19 government troops, a rebel spokesman said on Monday.

"There was heavy fighting on Saturday in Warni, in the far east of Talodi locality. The SPLA repelled an attack by the army. They left 19 bodies on the ground," Arnu Ngutulu Lodi told Agence France Presse.