By Hereward Holland
JUBA (Reuters) - Several thousand South Sudanese rebels have surrendered to the government and returned home from alleged rear bases in neighboring Sudan, government and rebel officials in the south said on Friday.
South Sudan has been struggling to contain insurgencies it claims have been supported by Sudan since it gained independence from its northern neighbor in 2011 under a peace deal that ended one of Africa's longest civil wars. Sudan denies the allegations.
The north declined to comment on the rebels' surrender, which follows the two countries agreeing to resume southern oil exports through the north and pledging not to support insurgencies on the other's territory.
The South Sudan Liberation Army (SSLA), one of the largest rebel groups in the new country, and two other militia groups said they had accepted an amnesty offer from President Salva Kiir.
South Sudan's army said some 3,000 rebels crossed the border from Sudan where they were believed to have training bases, along with 100 vehicles, including 37 trucks mounted with machine guns and anti-aircraft guns.
"Our forces have joined the peace process with the South Sudan army," SSLA spokesman Gordon Buay said.
Sudan's army spokesman al-Sawarmi Khalid declined to comment, saying only that international peacekeepers monitoring the border could confirm any crossing.
Incidents in the remote border area are hard to verify.
Security analysts say hundreds of people were killed in clashes between the SSLA and Southern government forces in November 2011 and March 2012 in Unity State, although the group has not been active recently.
Tension has plagued ties between the two countries since their messy divorce following a peace deal in 2005 that ended more than 20 years of civil war, with deadly border clashes breaking out a year ago.
While Khartoum has accused Juba of backing rebels in two northern border states and its western region of Darfur, South Sudan has long said Sudan was backing militias on its territory.
South Sudan's army spokesman Philip Aguer said the rebel surrender might be linked to this month's visit of Sudan's President Omar Hassan al-Bashir to Juba during which he pledged to normalize relations.
"If Sudan was still hostile, it would have attacked them because they were moving with a lot of equipment," Aguer said.
Aguer said this was the largest surrender since 2006, when rebels led by Paulino Matip capitulated.
"(This) is a significant development toward improved relations between Sudan and South Sudan. It shows that concrete deals were signed during Bashir's recent visit to Juba," said Jonah Leff, a regional analyst for the Small Arms Survey.
(Additional reporting by Ulf Laessing in Khartoum; Editing by Hugh Lawson)