Ukraine's national oil and gas company Naftogaz Ukrainy has sent Russian gas giant OJSC Gazprom a draft of a supplement agreement that envisions changes in the conditions of the contract between the two companies, including the prices, volumes and conditions of natural gas shipments.

Naftogaz's press service said in a statement that the changes Ukraine was proposing to the January 19, 2009 buy-sell agreement for natural gas between 2009 and 2019 "will allow for all disputes concerning Russian gas imports to be resolved."

The statement does not specify the price or other details of the changes Ukraine is suggesting for the contract.

The company's press service said the fourth round of three-sided talks between Ukraine, Russia and the EU would take place on June 2 concerning shipments of Russian gas to Ukraine.

"Naftogaz Ukrainy is set on continuing talks with Gazprom in a constructive manner," the company said.