BERLIN - Cologne Cathedral, one of the most renowned German landmarks and UNESCO World Heritage Site, is now starting to quiver as a nearby subway line went into operation, according to church officials.

"The effects can be felt, measured and heard," Cathedral Provost Norbert Feldhoff said in a statement on Wednesday, adding that "it cannot be ruled out that these effects will cause long term damage to the building."

Visitors have reported vibrations felt on the floor and the outside steps as the city's No. 5 subway line arrived at the new Dom/Hauptbahnhof station. Earthquake-measuring sensors in the building have confirmed the vibrations.

Cathedral officials and transport representatives agreed at an emergency meeting on Wednesday that trains would slow down to 20 km per hour from the planned 30 km per hour when driving through nearby tunnel section. A working group was also set up to seek other measures to stop the shake and noise, Feldhoff said.

The cathedral, build over six centuries from 1248 to 1880, endured the World War II although damaged by Allied bombers. It was enshrined as a UNESCO World Heritage Site in 1995.

A UNESCO spokesman told local news magazine Der Spiegel that the organization had not been informed of the problems with the cathedral, adding that the World Heritage Committee would look into it.