KIEV, June 1 – A switch to payment in advance for gas supplies could result in the suspension of transit shipments via Ukraine's territory, according to an official from the Ukrainian Presidential Secretariat.

Roman Zhukovsky, the head of the secretariat's main social and economic development service, made the claim on the Inter TV channel on May 30.

"If we want to have our own gas, we should halt the transit, because the gas will be moving in the opposite direction from the one it is today," he said.