KHARTOUM - The United Nations on Friday flew ailing Darfur rebel leader Suleiman Jamous out of Sudan en route for Kenya, ending his 15-month ordeal at a U.N. hospital in central Sudan, where he was under effective house arrest.

Jamous, the humanitarian coordinator of the Sudan Liberation Movement (SLM), was the key liaison between rebels and the world's largest aid operation, which has been helping some 4.2 million people in Darfur.

The United Nations had moved him to the hospital in the central town of Kadugli more than a year ago without informing Khartoum. Sudan called him a criminal and said it would arrest him if he left U.N. care.

"He left today for Kenya," said Radhia Achouri, a U.N. spokeswoman in Sudan.

Shortly before leaving Kadugli, Jamous told Reuters: "I was kept illegally for such a long time. At last I have had the possibility to get out of this dilemma."

"I feel pleased, very pleased. But the experience of being kept illegally was very bad," he added.

Jamous needs a stomach biopsy which could not be performed in the U.N. hospital.

"The pain is there. It is not severe. Thanks to the help of some people here and to ease the pain, it is bearable," he said.

Jamous is respected in Darfur and considered a consensus builder who could help peace efforts and unify rebel groups.

Since a 2006 peace deal signed by only one of three negotiating rebel factions, the insurgents have split into more than a dozen groups, creating chaos in Darfur.

Peace negotiations between the government and the rebels are due to open on Oct. 27 in Libya. The majority of the rebel groups have agreed to attend the talks, but Abdel Wahed el-Nur, founder of the SLM, has said he will not go.

On a visit to Rome, Sudanese President Omar Hassan al-Bashir said on Friday his government was willing to observe a ceasefire in Darfur from the start of the talks.

Jamous said he would continue to work for peace in Darfur regardless of the state of his health.

"The civilians of Darfur, they badly need peace. But the government and the rebels are still violating the ceasefire that they signed before," he said.

"They have got to get together in these peace talks to end the suffering of the people of Darfur," Jamous added.

The violence in Darfur escalated this month after rebels accused government forces of bombing villages. Sudanese troops and rebels also clashed in Haskanita in southeastern Darfur. The battle resulted in casualties on both sides.

International experts estimate some 200,000 people have died and 2.5 million have been driven from their homes in more than four years of fighting in Darfur. Khartoum disputes the figures.

Sudan gave the green light for Jamous to seek medical treatment abroad after a campaign by international activists, which culminated in a letter to Bashir on July 30, signed by 11 prominent figures.

They included South African Archbishop Desmond Tutu, former U.S. ambassador to the United Nations Richard Holbrooke, former Czech President Vaclav Havel and Nobel Peace Prize Laureate Jody Williams.

"He exemplified the best tradition of civic activism in Sudan including personal piety and self-sacrifice in the cause of providing essential assistance to those in need," they wrote.

In August, American actress Mia Farrow offered her freedom in exchange for that of Jamous.

During his visit to Sudan early this month, U.N. Secretary General Ban Ki-moon said he had secured a personal pledge from Bashir to let Jamous leave the country on humanitarian grounds.