Russia’s Gazprom gas monopoly has threatened to halve supplies to Belarus tomorrow in a payment dispute that could disrupt deliveries to western Europe.

Moscow said yesterday it would cut by 45% supplies flowing to its neighbour through export pipelines – which also carry gas to Germany, Poland and Ukraine – if Minsk did not pay debts of nearly $500m by 10am on Friday.

Gazprom said exports to the European Union would not be affected but it is feared that Belarus may replace its deficit by siphoning off gas in transit.

This is not the first time Russia has cut supplies to its neighbours – it cut supplies to Ukraine for several days in what became known as the “gas war” in January last year. Belarus’s close ties to Russia have traditionally ensured it has cheap supplies.

But not any more.