Wintersteller is worried about those still being held

An Austrian kidnapped by suspected militants while trekking through the Saharan desert in Algeria has said he was nearing collapse before he and other tourists were rescued earlier this week.

"Our shoes were shredded and we were at the end of our physical strength," Gerhard Wintersteller, 63, told Germany's RTL television following his three-month ordeal.

He was unclear about the reasons for his kidnapping, which the Algerian authorities have linked to Osama Bin Laden's al-Qaeda network.

Mr Wintersteller said his kidnappers wanted to install an Islamic state in Algeria but also that they had been trying to get money through blackmail.

"They wanted ransom money - no political demands, as far as I know. They wanted money to get weapons," he said.

Mr Wintersteller who was captured in February while trekking in the Saharan desert was reportedly rescued by Algerian troops from a hideout of an opposition group, the Salafist Group for Preaching and Combat (GSPC).

Night flights

Mr Wintersteller described how he and his fellow hostages were constantly moved around the desert at night without the use of lights.

The group was taken to a wadi, or dried river valley, and held for four or five days, before being moved on to a similar hiding place.

Eight terrorists jumped out and held their Kalashnikovs in front of us Gerhard Wintersteller

"Then the intervals became shorter and shorter. They could feel that the military was on their trail," he said.

"At that stage we were fleeing every night, had to walk at night.

"When they said at around two or three in the morning: 'This is where we're camping,' we just fell down and spent the last hours of the night like that," he added.

The 32 Europeans who went missing in seven groups were all travelling along a 500-kilometre (320 mile) road which cuts through an arid region of rocky plains, canyons and mountains near the Libyan border.

Mr Wintersteller's group was travelling in four cars.

'Enormous shock'

They were kidnapped as they stopped to talk to a Germans travelling in a car coming from the opposite direction.

SALAFIST GROUP FOR PREACHING AND COMBAT Wants Islamic state in Algeria One of most hardline groups fighting government On US list of "terrorist groups" Grew out of Armed Islamic Group (GIA) around 1998 Profile: Algeria's Salafist group

"The shock was enormous because, as we stopped, eight terrorists jumped out and held their Kalashnikovs in front of us," he said.

"We had to throw ourselves on the ground. They ripped the car keys out of our hands."

Citing fears for the safety of the remaining hostages, he refused to comment on how they were treated by the kidnappers or on the circumstances in which they were freed.

As the German hostages arrived at Cologne airport late Wednesday, some of them leaned heavily on the handrail as they got off the plane.

Still searching

Axel Mantey, 30, was the first to emerge, sporting a beard and wearing Arab dress.

He was followed by his girlfriend, Melanie Simon, 25, in a bright pink robe, carrying a bouquet of flowers; while the Swede, Harald Ickler, 52, who lives in Bavaria, punched both arms in the air and gave a double victory sign.

The freed hostages appeared tired, but in good health

Mr Wintersteller was flown to Salzburg along with the other freed Austrians.

Concern however is mounting over the fate of 15 European tourists still being held by the militants.

The Algerian interior ministry said intense searches were under way to find and free the remaining hostages which, it said, were being held by "a second terrorist grouping".