"Nobody is going to deliver gas for free. It's just impossible. And you can only pay for it in rubles," Kremlin spokesman Dmitry Peskov said.
"The situation has changed against the backdrop of an economic war being waged against Russia," he stressed, "businesses (Russian gas commander) need to understand (it)."
In retaliation for European sanctions adopted because of the Russian offensive in Ukraine, President Vladimir Putin announced last week that Russia would only accept rubles as payment for gas deliveries to the EU, giving a week to Russian authorities to work out a new ruble settlement system.
On Monday, the G7 countries said that demanding payment in rubles for Russian gas is "not acceptable", according to an announcement by German Economy Minister Robert Habeck, who called on the companies concerned to "not not respond to Putin's request" and called Russia an "unreliable supplier".
"Russia has always been, remains and will remain a reliable supplier of hydrocarbons," Peskov retorted again on Tuesday.
On Thursday, the Russian government, the Central Bank and the Russian gas giant Gazprom are due to present Vladimir Putin with a report on the establishment of the ruble payments system.
Russian gas is crucial for the EU, which has been seeking since the beginning of the Russian offensive in Ukraine to find the means to get rid of this dependence.
The decision to switch to ruble invoicing allows Russia to support its national currency, which has been heckled by sanctions, but will deprive it of a very important source of foreign currency.
However, this implies a revision of existing supply contracts.
© 2022 AFP