A new four-nation economic bloc appeared at the start of 2015, promising free movement of goods and services across an area that is home to more than 170 million people, but no fanfare marked the occasion.

, but it was finally born in the midst of an economic and financial storm that is rattling its members – Russia, Kazakhstan, Belarus and Armenia – and doing nothing to encourage their neighbours to join the club.

Putin envisaged the Eurasian Union as “a powerful supranational association capable of becoming one of the poles in the modern world and serving as an efficient bridge between Europe and the dynamic Asia-Pacific region”.

Critics have long questioned the union’s political raison d’etre, suspecting it to be a Kremlin vehicle to reassert control over former Soviet states, but now its economic worth is under scrutiny as Russia’s currency and finances take a battering.

The sharp fall in world oil prices has hit energy-dependent Russia hard, while a dollar now buys twice as many roubles as it did this time last year.

Russia sold the equivalent of some €70 billion in foreign currency reserves last year to bolster its currency and spending cuts and soaring inflation are now expected as oil continues to sell for less than half the price envisaged in the state’s 2015 budget.

Western sanctions over Moscow’s role in destabilising Ukraine are adding to the pain.

The shockwaves are crashing around those former Soviet republics whose economies are still closely tied to Russia and which, in several cases, share its heavy reliance on oil, gas and other energy products.

Belarus president Aleksandr Lukashenko sacked his prime minister, central bank chief and other top officials in late December as fears of a bank run on the Belarusian rouble prompted the imposition of currency controls.

This month, Belarus’s central bank scrapped most of the restrictions on foreign currency transactions and raised its benchmark interest rate to 25 per cent – a first hike since 2011 – and devalued the rouble by a further 7 per cent.

As well as seeing its own rouble fall sharply against the dollar, Belarus complained of a dramatic drop in export revenue from Russia due to currency weakness there and demanded that future trade be conducted in dollars or euros.

Energy-rich Turkmenistan started 2015 by devaluing its manat currency by about 19 per cent against the dollar, the first such move since 2009, and also hiked petrol prices by 60 per cent as, across the Caspian Sea, Azerbaijan burned through some 8 per cent of its foreign currency reserves defending its own manat in December.

Analysts expect Kazakhstan to devalue its tenge currency early this year, possibly exceeding the 19 per cent devaluation imposed last February.

As well as having deep trade links with Russia, many former Soviet states rely on remittances sent home by migrants who work there – cash flow that could slow dramatically as Russia’s own economy shrinks and jobs vanish.