BRUSSELS: The European Union is discussing a possible new round of economic sanctions on Russia with the United States and Britain, but no decisions will be taken on Monday, the bloc's top diplomat said.

The European Union, along with the United States, imposed economic sanctions on Russia in July 2014, targeting its energy, banking and defence sectors, and is considering taking further measures if Russia tries to invade Ukraine.

"We are in deterrent mode," Josep Borrell told reporters as he arrived for a meeting of EU foreign ministers.

"In any case we will send a clear signal that any aggression against Ukraine will have a high cost for Russia... We are studying together with the US and the UK what (sanctions )could be, when and how, in a coordinated manner."

EU diplomats told Reuters the discussion was focused on a potential gradual increase of any sanctions, ranging from possible travel bans and asset freezes on powerful members of Russia's political elite and to banning all financial and banking links with Russia.

Sanctioning the Nord Stream 2 pipeline between Russia and Germany to prevent it becoming operational was also an option, as well as targeting more Russian state-owned defence and energy companies or cancelling natural gas contracts.

But envoys said such steps were likely to be considered only if the Russian military attempted a full invasion of Ukraine.

NATO Secretary-General Jens Stoltenberg has repeatedly warned Russia that the Western military alliance is standing by Ukraine amid a large and unusual concentration of Russian troops on Ukraine's borders.

Russia says it has no intention to invade Ukraine and accuses Kyiv of deploying half of the Ukrainian army to confront pro-Russian separatists in the east of the country.