Tennis player Novak Djokovic has made an emotional plea for help, as tens of thousands of people in Bosnia and Serbia continue to be affected by a "total catastrophe of biblical proportions".

Djokovic made the appeal on Saturday in Rome, where he was competing in the Italian Open semi-finals, days after heavy rainfall and flooding killed at least 20 people in both countries and forced many more from their homes.

It is the worst flooding in the Balkans since records began 120 years ago.

"This rain that has been falling constantly for four (days) is going to stop eventually and after that there is a minimum of several months of recovery," Djokovic told reporters after winning the match against the Canadian player Milos Raonic.

"People are without homes and need any kind of help. This is a total catastrophe of biblical proportions. Half of the country is in danger of not having any electricity, we're talking about whole cities, not villages, that are being evacuated.

"Yes I'm happy that I'm in the final but I'm feeling a bit uncomfortable because there's so many sportsmen back in my country for whom everything have been stopped. They're helping and I'm not able to do that," Reuters news agency reported him as saying.

He also criticised international news networks for not giving enough airtime to the crisis.

"I see on CNN and BBC and other big networks there’s a lot of talk about the miners in Turkey and so forth and it’s another disaster.

"But no broadcast about Serbia and this is the biggest flood that I’ve ever seen and maybe that Europe has ever seen. This is incredible. So I hope people can find the common sense and broadcast this a little bit and spread the awareness of what’s going on."

In 2010, flooding caused havoc across Albania, Bosnia, Serbia and Montenegro, forcing the evacuation of thousands from their homes.

Source: Agencies