KIEV (Reuters) - U.S. President-elect Donald Trump and Ukrainian President Petro Poroshenko agreed during a telephone call to hold a bilateral meeting, Poroshenko's office said on Tuesday.

It said Poroshenko also stressed the need for resolute U.S. support of Ukraine in countering what it called Russian aggression. It did not specify when a meeting could take place.

Ukrainian authorities are laying the groundwork for Poroshenko to visit Washington early next year, hoping to shore up U.S. support against Russia and allay concerns about what a Trump presidency means for Kiev.

(Reporting by Matthias Williams; editing by Mark Heinrich)