BERLIN, June 4 (Reuters) - Thousands of people were

evacuated from central Cologne in western Germany on Wednesday

following the discovery of three wartime bombs, in what the city

authority called the largest such operation since the end of

World War Two.

An evacuation zone with a radius of 1,000 metres (1,100

yards) was cleared from 8 a.m. (0600 GMT), impacting around

20,500 residents along with many workers and hotel guests in the

city's old town and Deutz district.

Three American bombs, each with impact fuses, were found

during construction work on Monday in Deutz, a bustling area on

the bank of the River Rhine.

Bomb disposal experts plan to disarm the ordnance later on

Wednesday.

Unexploded bombs are often found in Germany, where many

major cities sustained heavy damage during the war.

The evacuation area includes one hospital, two retirement

homes, nine schools, and many hotels and museums.

"Everyone involved hopes that the defusing can be completed

in the course of Wednesday. This is only possible if all those

affected leave their homes or workplaces early and stay outside

the evacuation area from the outset on that day," the city

authority said in a statement.

The measures caused major transport disruptions in the city

of over a million people, with Germany's national rail operator

warning that many trains would be diverted or cancelled.

A stretch of the Rhine will be blocked off before the bomb

disposal operation begins.

The Rhine, which runs from the Swiss Alps to the North Sea

via Cologne, is one of Europe's key waterways for the

transportation of commodities such as grain and coal.

Private television station RTL, whose main

office is located in the evacuation zone, interrupted its

morning news programme.

"We have to leave," the news anchor said, grabbing his

bag as the lights were turned off.