The US government says it will not accept Russia's annexation of the Crimean peninsula from Ukraine.

US Secretary of State Mike Pompeo looks on as Senators ask questions during a Senate Foreign Relations Committee hearing in Washington, DC on July 25, 2018.
US Secretary of State Mike Pompeo looks on as Senators ask questions during a Senate Foreign Relations Committee hearing in Washington, DC on July 25, 2018. (AFP)

The United States will not recognise Russia's annexation of Crimea, US Secretary of State Mike Pompeo said on Wednesday, seeking to quell suggestions that Washington could accept Moscow's 2014 occupation of the Ukrainian peninsula.

In a "Crimea Declaration" issued shortly before his testimony to a Senate committee, Pompeo restated US policy rejecting the annexation.

The statement followed widespread criticism in the United States of a private meeting between US President Donald Trump and Russian President Vladimir Putin in Helsinki and questions from Congress about what Trump agreed to in the one-on-one talks.

"The United States rejects Russia's attempted annexation of Crimea and pledges to maintain this policy until Ukraine’s territorial integrity is restored," Pompeo said in the statement.

"The United States calls on Russia to respect the principles to which it has long claimed to adhere and to end its occupation of Crimea," he said.

Pompeo later reassured senators that the United States would not lift sanctions against Russia until Moscow returned control of Crimea to Ukraine.

Russia's Foreign Ministry quickly dismissed Pompeo's comments. "We know the worth of such momentous declarations," ministry spokeswoman Maria Zakharova said on her Facebook account.

Speaking after the summit, Putin said Trump believed that Russia's annexation of Crimea was legal, based on a referendum.

Trump generated fierce criticism following his summit with Putin after he appeared to give credence to the Russian leader's assertion that Moscow did not interfere in the 2016 US presidential election.

Lionel Donovan has the latest from Washington DC.

White House national security adviser John Bolton said on Wednesday that Trump would postpone a second meeting with Putin until next year after a federal probe into the alleged meddling is over.

"The president believes that the next bilateral meeting with President Putin should take place after the Russia witch hunt is over, so we’ve agreed that it will be after the first of the year," Bolton said in a statement.

During testy exchanges with members of the Senate Foreign Relations Committee, Pompeo declined to offer details of what he had been told by Trump about the Helsinki meeting. He said conversations between the president and his cabinet should remain private.

"You come before a group of senators today who are filled with serious doubts about this White House and its conduct of American foreign policy," the committee's chairman, Republican Bob Corker, said in opening remarks.

Pompeo confirmed, however, that Trump and Putin had discussed solutions to the war in Syria, where Moscow and Iran have supported forces of Syrian regime leader Bashar al Assad.

"We are working to see if we can’t get Russia to be more co-operative in terms of driving toward a political resolution that would take down the violence levels and create some opportunity to begin a political resolution of the process in Syria," said Pompeo.

Source: Reuters