BERLIN - Germany and the Czech Republic on Monday signed a joint declaration, pledging to overcome Russian fossil fuel dependency and to accelerate the transition to low carbon energy as falling Russian gas imports threaten security of supply across Europe.

Also on Monday, the biggest single pipeline carrying Russian gas to Germany began annual maintenance, with flows expected to stop for 10 days, but governments, markets and companies are worried the shutdown might be extended because of the war in Ukraine.

"We are going to finalise the agreement on solidarity measures to safeguard the security of gas supply between our countries prior to the start of the upcoming winter season," the declaration read.

German Economy Minister Robert Habeck, on a visit to Prague, and Czech Industry Minister Jozef Sikela said it was necessary to prepare for various options, including that deliveries through the Nord Stream 1 gas pipeline would not resume when scheduled maintenance is due to finish on July 21.

(Reporting by Robert Muller and Riham Alkousaa, Writing by Miranda Murray, Editing by Kirsti Knolle and Barbara Lewis)