MOSCOW — For two months, Jordi Sarda Bonvehi negotiated with Ukrainian officials on behalf of a Spanish utility company about participating in a $1 billion investment fund to build a liquefied natural gas plant on the Black Sea.

On Monday, he took part in a signing ceremony for the deal overseen by the prime minister in Kiev, the Ukrainian capital.

The only problem is that the utility company, Gas Natural Fenosa, has never heard of him.

“Gas Natural has not signed any contract to invest in an L.N.G. plant project in Ukraine, nor is it leading any consortium whatsoever,” the company said in a statement soon after the ceremony. “Gas Natural Fenosa has nothing under study in this regard, nor does it have representatives working in Ukraine on this issue.”

Ukrainian officials have now conceded that Mr. Bonvehi, if that is indeed his real name, is certainly not a representative of Gas Natural.