* U.N. orders rebels halt offensive
* Key border town in rebel hands as soldiers withdraw to Algeria
* Some 60,000 now displaced by fighting (Adds U.N. call, government confirmation, refugees)
By Tiemoko Diallo and Adama Diarra
BAMAKO, Feb 8 (Reuters) - The United Nations called on rebels in northern Mali on Wednesday to halt their offensive, shortly after they seized the strategic border town of Tinzawatene and forced government troops to withdraw into Algeria.
The fighting in the remote northeastern town followed a three-week desert advance by a Tuareg-led rebel force, helped by Malians returning from the Libyan conflict, which has forced nearly 60,000 civilians to flee their homes.
"The Secretary-General condemns the use of violence as a means to achieve political objectives," a spokesman for U.N. Secretary-General Ban Ki-moon said in a statement.
"He therefore calls on the rebel groups to immediately cease their attacks and to engage in dialogue with the Government of Mali to resolve their grievances," the statement added.
The seizure of Tinzawatene by the Tuareg-led MNLA rebels, who say they are fighting to create an independent state in north Mali, is a significant gain as it gives them control of a key transit and smuggling point in the desert.
The rebels have said they are open to talks, but only over the question of independence for north Mali. The government in Bamako has rejected any idea of a breakaway and said talks could only take place after the rebel push had been halted.
The government issued a statement on Wednesday confirming that its soldiers had withdrawn from Tinzawatene into neighbouring Algeria after several days of rebel attacks.
It said the troops carried out a "tactical withdrawal" from their military base near the Algerian border. One soldier had been killed and two wounded in the fighting, it added.
Hama Ag Sid'Ahmed, a rebel spokesman, said the rebels were in control of the town's two military camps and had seized several armoured and other military vehicles. One rebel had been killed and one wounded the fighting, Ag Sid'Ahmed said.
The rebels have pushed south on three fronts since fighting erupted in mid-January.
The International Committee for the Red Cross said the number of Malians displaced within the country had risen to 30,000, and a further 15,000 had crossed into Niger.
Mauritanian aid officials have said at least 5,000 Malians have crossed westwards over the shared border. Burkina Faso, Mali's southern neighbour, said it had welcomed over 8,000 refugees from the conflict.
The fighting has dispersed civilians in search of food and shelter across a region that the U.N. has warned is on the brink of yet another round of food shortages of its own.
Before the rebellion started, northern Mali was already awash with smugglers and home to a small but powerful group of fighters linked to al Qaeda. (Additional reporting by Mathieu Bonkoungou in Ouagadougou; Writing and additional reporting by David Lewis in Dakar; editing by Tim Pearce)