MOSCOW (Reuters) - Preparations for a meeting between Russian President Vladimir Putin and U.S. President Donald Trump are at an "advanced stage", Russian state news agency RIA quoted a senior lawmaker as saying on Thursday.

U.S. President Donald Trump's special envoy for Ukraine and Russia, Keith Kellogg, had a "thorough discussion" with Ukraine's ambassador to Washington in their first official meeting on Thursday, the ambassador said.

That will take some doing. Putin remains uninterested in peace talks as long as Russian troops continue to gain ground in Ukraine’s east, albeit at a slow pace, and while Ukrainian forces hold seized territory in the Kursk region inside Russia, according to John Herbst, a former U.S. ambassador to Ukraine, and other former officials.

The Kremlin said on Friday there had been a lot of inaccurate reports on U.S. plans for ending the Ukraine war and called for patience as speculation swirled around the timing of a possible meeting between presidents Vladimir Putin and Donald Trump.

Russian President Vladimir Putin and U.S. President Donald Trump have yet to discuss a possible meeting, CNN quoted Kremlin spokesman Dmitry Peskov as saying. It cited Peskov as saying there had been no initial contacts between the two leaders about whether such a meeting was needed or where and how it might take place if it did happen.