US president Donald Trump has tweeted that "it is time to move forward in working constructively with Russia!" after his G20 meeting with Vladimir Putin.

Mr Trump said he "strongly pressed" the Russian president twice over Russian meddling in the 2016 US election during their lengthy meeting at the world leaders' summit in Germany.

He said Mr Putin "vehemently denied" the conclusions of American intelligence agencies.

Mr Trump did not say whether he believed Mr Putin, tweeting that he has "already given my opinion."

Russia's foreign minister told reporters in Germany that Mr Trump took Mr Putin at his word over meddling, and US officials have not challenged this statement.

Mr Trump said previously he believed Russia was likely to have been involved in election hacking, but that other countries were too.

Mr Putin said he left the meeting thinking that Mr Trump believed his in-person denials.

"He asked questions, I replied. It seemed to me that he was satisfied with the answers," said Mr Putin.

US secretary of state Rex Tillerson, who took part in Mr Trump's meeting, had suggested that the two sides effectively agreed to disagree on the meddling question so they could proceed to address other pressing issues like the civil war in Syria.

Officials announced during the trip that the two sides brokered a ceasefire in southern Syria that went into effect on Sunday.

Mr Tillerson told reporters: "We did not expect an answer other than the one we received".

Mr Trump tweeted that the two sides also agreed to create a cyber security task force to ensure that "election hacking, & many other negative things, will be guarded."

He also said US sanctions on Russia were not discussed during the meeting and that "Nothing will be done until the Ukrainian & Syrian problems are solved!"