April 26 (Reuters) - Russia's top oil company Rosneft offered oil products from its refineries for loading during May-June in a tender requiring pre-payment in roubles, three market sources told Reuters on Tuesday.

As Russia seeks to offset the impact of Western sanctions imposed on the country over its invasion of Ukraine, President Vladimir Putin has demanded that buyers of gas sold by Russian gas monopoly Gazprom pay in roubles. Rosneft has followed on the footsteps of Putin's orders to Gazprom and asked for 100% prepayment and conversion of the payment into roubles for purchases of its oil.

Last week Rosneft offered 6.5 million tonnes of crude oil via tenders for loading in May-June, seeking full pre-payment in roubles for the first time. However, it failed to secure any sales as terms proved hard to meet, Reuters sources said.

Even so, Rosneft required the same terms for its oil product volumes, Reuters sources citing the tender documents said.

The company also gave buyers the option, where it is not possible to pay in roubles, to pay in Chinese yuan, U.S. dollars, euros, United Arab Emirates dirhams and Turkish lira, the sources said. These options, however, would be subject to negotiation and could be refused by Rosneft.

Bids were invited for about 2 million tonnes of fuel oil and vacuum gasoil (VGO), 1.4 million tonnes of naphtha and 1 million tonnes of marine diesel oil (MDO), traders added.

The tenders closed on April 25 and the results should be announced no later than May 13, the sources said.

Most of Rosneft's oil product volumes loading in 2022 had been sold via term contracts to buyers, but recently many of them decided to cut buying of Russian oil products amid caution about Western sanctions and issues with payments and shipping.

The European Union has not imposed a ban on imports of oil products from Russian refineries yet but it is considering options to cut imports of Russian oil as part of sanctions over the invasion of Ukraine, which Russia calls a "special military operation."

(Reporting by Reuters Editing by David Goodman and Susan Fenton)