Kiev: A business card brandished by pro-Russian separatists in eastern Ukraine as proof that a deadly attack on their checkpoint was the work of ultra-nationalists quickly became an object of derision on the internet.

Following the attack on a pro-Russian checkpoint near the flashpoint town of Sloviansk, self-proclaimed mayor Vyacheslav Ponomaryov presented a business card to the international press he said was proof of the involvement of the ultra-nationalist group Pravy Sektor, or Right Sector.

The red and black card purportedly belonged to group leader Dmytro Yarosh and was allegedly found in a burnt-out car near the site of the attack, in which at least two pro-Russian rebels were killed on Sunday.

But many pro-Western Ukrainians found it difficult to take the claim seriously. Within hours, a spate of mocked-up images had appeared, and a hashtag in Ukrainian meaning "Yarosh business card" was trending on Twitter.