The Russian ambassador to Britain, Alexander Yakovenko, has called Western sanctions against Moscow "illegal, unreasonable and counterproductive".

The US and the European Union have imposed several rounds of sanctions on Russian businesses and individuals over Ukraine. The new EU sanctions to block Russia's "access to capital markets",, dominated by Britain's banking sector, will target business worth up to £6billion a year in bonds issued by Russian state-owned banks and financial institutions in European markets.

Some Western states are now pondering whether to impose further sanctions that would affect whole sectors of the Russian economy after the downing of a Malaysian airliner in eastern Ukraine - a territory controlled by pro-Russian rebels - killing all 298 people on board.

But Yakovenko slammed the West by saying he "doesn't like sanctions" during a press conference at the Russian embassy in London.

"In my view, the sectoral sanctions against Russia may well trigger the long-anticipated end-game of the present global crisis. Is it the ultimate objective?" he asked.

"What is more, these sanctions send the wrong message to Kiev who continues its punitive operation [sic]".

The Russian ambassador accused the US of basing its theories on the MH17 crash on pictures produced on social media, with no evidence to back them up. "It is striking how much Washington relies on social media stuff," he said.

Russia rejects suggestions that the pro-Russian rebels, blamed by Western governments for shooting down Flight MH17, owned a Russian-made anti-aircraft missile (Buk), and said the rebels lacked the training to use such a system.

US officials told the Wall Street Journal that the separatists who downed the commercial airliner over the Donetsk region used the Buk system.

"It's unacceptable to assign blame for MH17 crash until facts of investigation are known," he said.

"I think the local de facto authorities carried out the operation dealing with the consequences of the tragedy with the utmost efficiency, given the conditions of civil war, limited resources and the scale of the disaster.

"We want to see other evidence [from the US and UK]. As soon as we get this, then we'll have a full picture."