River levels in the Czech Republic have risen sharply overnight after the authorities were forced to open several dams in the south of the country.

In the capital Prague, flood barriers have been raised to cope with the extra water on the River Vltava.

At least seven people have died in the Czech Republic and two in Austria after severe flooding and days of heavy rain.

Germany has drafted in the army to help with flood defences. Several cities have declared states of emergency.

In the Bavarian town of Passau, floodwaters have now reached a level not seen since the 16th Century, making much of the town inaccessible.

Charles Bridge Closed

In the Czech Republic, a nationwide state of emergency is in force, with water levels expected to peak later on Tuesday.

Around 3,000 people have been forced to leave their homes across the west of the country.

On Monday morning, the River Vltava was flowing at 2,800 cubic metres per second - 10 times its normal volume - through Prague's historic centre.

As a precaution, the city's metro system and central sewage treatment plant were closed, metal flood defences were erected and sandbags built up along the banks of the Vltava.

The Charles Bridge - normally packed with tourists - has been closed and tigers at the city's zoo were even tranquilised and moved out of an enclosure thought to be at risk.

By Monday evening, the people of Prague had thought the worst was behind them, reports the BBC's Rob Cameron in the capital.

But then Prime Minister Petr Necas announced unexpectedly that a system of nine dams called the Vltava Cascade was dangerously full, and the pressure would have to be relieved.

At 20:00 local time (18:00 GMT) the floodgates on several dams were opened.

Our correspondent says the Vltava in Prague is now rising again, the situation exacerbated by several swollen tributaries.

Firemen and soldiers are raising the city's flood defences again to cope with the extra volumes of water on the Vltava, which has already burst its banks in several places.

North of Prague, further downstream, the River Elbe is rising to levels approaching those seen in 2002, the last time Europe experienced similar floods.

Seventeen people were killed in the Czech Republic then and the cost of the damage across the continent was estimated at 20bn euros (£17bn).-BBC