"Unfortunately...the Minsk accords have not been respected, if we move forward it's only a few millimetres at a time, sometimes we move backwards," the chancellor said during a visit to Kiev, referring to the 2015 agreement designed to end the conflict.

"Germany will therefore advocate that these sanctions are upheld," she said during a press conference with Ukrainian President Petro Poroshenko.

"Russia must do a simple thing: leave Ukraine, pull out its troops, withdraw its arms and restore the territorial unity of the country," Poroshenko told journalists.

He denounced elections set for 11 November in the self-proclaimed republics of Donetsk and Lugansk in the east of the country.

"We have condemned the Russian Federation's organisation of these fake elections," Poroshenko said.

"It is a clear sign the Kremlin is not ready for a peaceful solution."

Merkel's one-day trip to Kiev was her first since the signing of the Minsk accord, which has so far failed to achieve its aim of bringing peace to eastern Ukraine.

The European Union and the US have imposed heavy sanctions on Russia over the annexation of Crimea in 2014.

Moscow has also been accused of fuelling a rebel conflict in eastern Ukraine that has cost the lives of some 10,000 people, a charge it denies despite substantial evidence to the contrary.

The two leaders also discussed the controversial Nord Stream 2 gas pipeline.

The pipeline -- which has been heavily criticised by Kiev, the US and several European nations -- is set to bypass Ukraine to bring supplies direct from Russia to Germany.

Nord Stream 2 aims to double the capacity of Nord Stream 1 by the end of 2019.