Poland has said it "will manage" after what it says are Russian threats to cut gas supplies to the country.

Poland and Bulgaria said Russian energy firm Gazprom told them it would stop supplying gas to "unfriendly" countries that refuse to pay in roubles.

Data from the European Union network of gas transmission operators shows that Poland's supply was briefly cut on Wednesday, but has since been resumed.

Early on Wednesday Bulgaria said gas continued to flow for the time being.

Both countries have refused to pay in roubles - the Russian currency - as demanded by Russian President Vladimir Putin.

Polish state gas company PGNiG said it had been told all gas deliveries would be halted from 08:00 CET (06:00 GMT). The Bulgarian Energy Ministry also said it had been informed deliveries would be suspended from Wednesday. 

PGNiG bought 53% of its gas imports from Gazprom in the first quarter of this year, but Warsaw says it can get gas from other sources.

It described the suspension as a breach of contract, adding that the company would take steps to reinstate the gas supply.

Bulgaria, which relies on Gazprom for more than 90% of its gas supply, also said it had taken steps to find alternative sources but no restrictions on gas consumption were currently required.

The country's energy ministry said Bulgaria had fulfilled its obligations under the current contract with Gazprom and made all required payments.

It added that the new payment system proposed by Russia was in breach of the existing contract.

Following the news, Poland's climate ministry said the country's energy supplies were secure. 

Climate Minister Anna Moskwa said there was no need to draw gas from reserves and gas to customers would not be cut.

Poland's Deputy Foreign Minister, Marcin Przydacz, said his country had been preparing for the possibility Russia might limit gas exports by diversifying its supplies.

"I'm pretty sure that we will manage to handle this," he told the BBC.

He added that the suspension proved Moscow was "not a reliable partner in any kind of business" and urged other European nations like Germany to support a ban on Russian energy imports.

Poland was already planning to stop importing Russian gas by the end of the year, when its long-term supply contract with Gazprom expires.

PGNiG said its underground gas storage was almost 80% full and, with summer approaching, demand was lower.

Poland also has alternative supply sources, including a liquefied natural gas (LNG) terminal in Swinoujscie.

On 1 May, a new gas pipeline connection with Lithuania is also due to open that will give Poland access to gas from Lithuania's LNG terminal.

And a new pipeline delivering gas from Norway, known as the "Baltic Pipe", comes online in October. It should reach full capacity by the end of the year and could replace all Russian deliveries.