Russian President Dmitry Medvedev on Wednesday said it would be "irresponsible" to change existing gas supply contracts between Russia and Ukraine, according to Reuters.

"We have signed a treaty this year for 10 years ... I think that proposals to change them are irresponsible," Medvedev said in comments broadcast live on television channel Vesti-24. "Despite talk that something is happening, that the (Ukrainian) president is not working, the Ukrainians are paying every month and this makes me happy," Medvedev said.