People evacuate themselves in a boat in the town of Lazarevac, south from Belgrade. Picture: Marko Djurica

 Sarajevo, Bosnia-Herzegovina - Samira Mahmic thought she was getting her life back when she was winched into a helicopter with her 10-year-old son clinging to her amid the worst flooding in more than a century in the Balkans.

But she froze when she realised the helicopter was now fully loaded and she looked down to see her 17-year-old daughter Amina, watching in disbelief as the aircraft left her behind on a roof sticking out of a sea of water.

“I thought they would go back but it got too late last night,” Mahmic said on Friday.

Luckily her daughter's mobile phone still had some battery on Friday morning and Mahmic was able to reassure herself that her daughter and husband were both still alive.

“It's Judgment Day in Maglaj,” Mahmic said of her northern Bosnian hometown that was hit by the heaviest rainfall since measuring started 120 years ago.

Rain-swollen rivers across the Balkans have flooded roads, cut off power and caused more than 200 landslides.

Both Bosnia and Serbia have requested international help. The EU said its Civil Protection Mechanism has been activated and Germany, Bulgaria, Austria and Slovenia have already offered assistance.

“In three days, as much rain fell as normally falls in three months,” said Goran Mihajlovic, of Serbia's Meteorological Institute.

“Statistically, such rainfall happens once in 100 years,” he added.

In Serbia 6 000 people have been forced out of their homes. A Russian emergency team has flown in to join the rescue efforts. In Bosnia, the EU force and the Bosnian Army are waiting for improved visibility to resume helicopter evacuations.

Mahmic sobbed as she described seeing from the helicopter on Thursday people on roofs and balconies waving baby clothes, signaling they are trapped with small infants. Water had reached second floors.

Fahrudin Solak, the head of the rescue team trying to enter Maglaj by road, said for the third night in a row his people were not getting out of bulldozers.

“We are just handing them sandwiches and juices as they are pushing the machines through the debris of a landslide,” he said.

“But we will save that town,” he added. - Sapa-AP