SOFIA - Two female migrants found dead in a mountainous rural region of Bulgaria died due to freezing conditions, authorities said Sunday, as asylum seekers continue to try to reach the EU despite harsh winter weather.

The women were part of a group of 19 migrants, including 11 children, found Saturday by border police near the southeastern town of Malko Tarnovo. Their nationality was still unclear.

"Two women have died - one younger and another middle-aged. Our border guards made every effort to help them, carrying them in their arms to try to warm them up, but it happened because of the cold," Interior Minister Rumyana Bachvarova announced Sunday told private bTV television. The area was under harsh winter conditions with high winds, some 30 centimetres (12 inches) of snow and freezing temperatures.

A ministry statement said one of the victims was a teenager - aged between 14 and 16 - and the other was between 30 and 40 years old. All of the children, aged between 4 and 16, were taken to hospital with frostbite and two adults were in critical condition, a hospital spokesman told Focus news agency.

This is the second report in Bulgaria this winter of migrants succumbing to cold, after the frozen bodies of two men were found in a mountainous area at Bulgaria's border with Serbia in January.

Meanwhile, four Iranian migrants making a rare attempt to reach Britain by boat from France on Saturday were rescued in the nick of time after their vessel took on water and was close to capsizing, officials said.

Rescuers were only alerted after one of the migrants made it back to the beach at Sangatte in northern France before dawn. He was in a dangerously cold state and asking for help for his four compatriots.

A search was launched and the boat with the four men was located with the help of a Belgian army helicopter, the French coastguard said. "Around 5:30 am (0430 GMT), a migrant on the beach at Sangatte in a hypothermic condition requested help and indicated that he had been on a boat with four other people," local authorities in the Pas-de-Calais region of northern France told AFP.

The man told rescuers that he and the four others had been trying to make it to Britain.

"Shortly after 7:00 am the little boat with the four men in it was located", the coastguard said. "They were really in extremis, we saved their lives, because they were on the point of capsizing. There were terrible waves and the boat had filled with water," said Bernard Barron, one of the rescuers.

Gilles Debove, of the local police union, said it was "extremely unusual" for migrants to try to reach Britain by the sea route.

"This must be the second or third time in 1- years," he said. "Crossing is very dangerous because it's a maritime highway. The Channel and the North Sea, it's not the Mediterranean."

The president of a local organisation supporting migrants, Christian Salome, told AFP he feared a rise in the number of attempted Channel crossings due to tighter security around the port of Calais making it more difficult for migrants to smuggle themselves across in lorries.

Around 3,700 migrants, mostly from Africa, the Middle East and Afghanistan live in the so-called "Jungle" shanty camp at Calais from where they hope to make the journey to Britain. A further 1,500 live in a camp at Grande-Synthe near Dunkirk.