A Ukraine dumpling-eating contest to find the person who could eat 10 of the dough balls most quickly went horribly wrong when the 77-year-old champion keeled over and died.

The winner, Ivan Mendel, had just won his prize, a one-litre jar of sour cream, when he began to feel ill.

"The old man got sick and fell to the ground," an unnamed witness told Interfax news agency. "The ambulance arrived when he was already dead. The doctor said that he probably choked on vomit."

The contest was held on Saturday in the south-east Ukrainian town of Tokmak as part of its city-day celebrations.

Dumplings, known in Ukraine as vareniki, are a staple of the regional diet; they are usually stuffed with mushrooms, potatoes or cherries. Organisers of the contest said the dumplings they used – filled with potatoes – had been frozen and packaged and bought from a local supermarket.

Organisers struck back at accusations that the contest had killed the man, saying Mendel had eaten just 10 dumplings in all. He ate them, reportedly, in half a minute.

"A 77-year-old pensioner ate his portion more quickly than his opponent," Viktor Khalamovsky, one of the contest organisers, told Interfax. "He won a prize for that – a jar of sour cream. What happened to him after his victory, the organisers don't know."

Officials in Tokmak, which is in the Zaporizhya region, refused to comment on the incident when contacted by local media, but said representatives had attended the Mendel's funeral on Tuesday.