MOSCOW: Russia has proposed extending by another year a current gas transit deal with Ukraine, its energy minister said on Friday.

"We proposed to our colleagues to extend the existing contract by a year on the current conditions," Russian Energy Minister Alexander Novak told reporters.

Yuriy Vitrenko, executive director at Ukraine's gas company Naftogaz, told AFP the firm had not received any offer from Russia.

Most of Russia's gas destined for Europe passes through Ukraine.

Ukraine wants to remain a major transit route for Russian gas while Moscow seeks to send more gas to Europe through the NordStream 2 and Turk Stream projects.

The transit agreement between Kiev and Moscow expires at the end of this year.

With the two countries at loggerheads over Crimea, Ukraine's territory annexed by Russia in 2014 and a separatist conflict in the east of the country, Moscow and Kiev have struggled to agree on the deal's extension.

Ukraine's seizure Thursday of a Russian tanker further ratcheted up tensions, with Moscow threatening unspecified "consequences".

Nord Stream 2, a 9.5-billion-euro ($10.6-billion) energy link between Russia and Germany, had been due to be launched in late 2019, but Gazprom has said it will now likely go online in 2020.

The consortium behind the project insists that Ukraine will retain its role as a transit country.