MOSCOW -- Moscow is ready to discuss a possible visit by President Vladimir Putin to Washington after a surprise invitation from President Donald Trump, Russia's ambassador to the U.S. said Friday. With confusion still swirling around what the two men discussed behind closed doors in Helsinki earlier this week, Ambassador Anatoly Antonov said it's important to "deal with the results" of their first summit before jumping too fast into a new one.

He said he hadn't seen Mr. Trump's invitation himself, but that "Russia was always open to such proposals. We are ready for discussions on this subject."

The Kremlin has the final say, but hasn't responded yet to the proposal Mr. Trump made Thursday.

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Antonov gave a few more details of what Mr. Trump and Putin talked about in Helsinki, but insisted that diplomatic discussions should remain discreet in order to be effective.

He notably acknowledged that the two men discussed a possible referendum in eastern Ukraine.

"This issue was discussed," he said, adding without elaborating that Putin made "concrete proposals" to Mr. Trump on solutions for the Ukraine conflict.

Mr. Trump tweeted that the two men discussed Ukraine but has not mentioned a referendum or revealed specifics of the Ukraine discussions. The U.S. and Russia have been on opposing sides of the conflict in Ukraine, unleashed after a popular uprising against a pro-Russian president and Russia's annexation of Crimea in 2014.

Ukraine and European powers are unlikely to support a referendum in the Donbass region, where pro-Russian separatists hold sway.

The Russian ambassador to Washington also denounced "anti-Russian anger" in the United States and reiterated denials of Russian meddling in the 2016 presidential election -- interrupting a questioner to say "We didn't interfere!"

He also reiterated denials of Russian involvement in the poisoning of former Russian spy Sergei Skripal in Britain.

Antonov called Monday's summit in Helsinki a "key event" in international politics and laughed off suggestions that the two men made any "secret deals."

Antonov gave details of their discussions on arms control, but said the U.S. has been reluctant to back Russia's proposals so far. He said the summit notably made progress on U.S.-Russian cooperation on Syria's future.

Meanwhile, Antonov also pushed for the release of a gun rights activist accused of being a covert agent in the U.S., calling her arrest a "farce."

U.S. federal prosecutors accused Maria Butina this week of being a covert Russian agent and working to infiltrate U.S. political organizations, including the National Rifle Association, before and after Donald Trump's election as president.

Butina, 29, denies wrongdoing, and the Russian Foreign Ministry started an online campaign for her release.