Foreign Minister Sergey Lavrov said during a news conference that U.S. newspaper reports about Trump withholding details of his meetings with Russia's president and an FBI investigation of whether he was working on Moscow's behalf reflected a plunge in journalism standards.
Trump said this week that he never worked for Russia and repeated his claim that an ongoing investigation of his ties to Russia was a hoax.
Asked if Russia would consider releasing minutes from President Vladimir Putin's one-on-one talks with Trump, Lavrov said doing so would defy the basic culture of diplomacy and dismissed the possibility.
Calls for Moscow to provide the minutes are illegitimate meddling in the U.S. president's constitutional right to conduct foreign policy, he said.
Putin's foreign affairs adviser, Yuri Ushakov, similarly derided media reports of Trump's possible promotion of Russian interests.
"What kind of nonsense are you asking about?" Ushakov snapped when asked if Trump was a Russian agent. "How can one comment on such a stupid thing? It has reached such a scale that it's awkward to even talk about it."
"How can a president of the United States be an agent of another country, just think yourself," Ushakov said at a briefing.
The Kremlin's hopes for better relations with the U.S. under Trump have been shattered by ongoing investigations into the allegations of collusion between Trump's campaign and Russia.
Ushakov said Russia-U.S. relations were currently at a level that "can't be worse."
Lavrov, who was speaking at a separate news conference, scoffed at the charges leveled against Trump's former national security adviser, Michael Flynn, saying Flynn only talked to the Russian ambassador to protect U.S. interests.
"It's quite obvious that the situation is absurd," Lavrov said of the investigation led by special counsel Robert Mueller.
He also criticized Trump for saying he intended to opt out of a key nuclear pact over alleged Russian violations.
Lavrov said the U.S. ignored Moscow's offer to inspect a Russian missile that Washington claimed violated the 1987 Intermediate-Range Nuclear Forces Treaty.
Russia made the offer during talks in Geneva this week, he said. U. S. negotiators stonewalled, repeating Washington's demand for Russia to destroy the 9M729 missile it claims runs afoul of the pact.
The United States says it will suspend its treaty obligations if Russian does not come into compliance by Feb. 2.
U.S. Undersecretary of State Andrea Thompson, who led the American side in the talks, said Wednesday that Moscow's offer was inadequate.
"To see the missile does not confirm the distance that missile can travel, and at the end of the day that's the violation of the treaty," she told reporters.
The treaty bans development, testing and deployment of land-based cruise and ballistic missiles with a range of 500-5500 kilometers (310-3140 miles).
Lavrov charged that the U.S. refusal to consider the Russian offer to have a close look at the missile reflects Washington's intention to abandon the INF treaty.
Questions of "why the Americans don't want to examine our proposals and get firsthand information about specific parameters of the missile were left unheard," he said.
Turning to last month's arrest in Moscow of Paul Whelan, a former U.S. Marine, on suspicion of espionage, Lavrov said the man's brother has visited Moscow and has been briefed about prison conditions. The Interfax news agency later carried the Foreign Ministry's statement saying that Whelan's brother isn't in the Russian capital.
The U.S. Embassy wouldn't comment.
Lavrov rejected the allegations that Russian authorities could have arrested Whelan in order to swap him for one of the Russians held in the U.S., saying "we don't do such things." He said Whelan was caught red-handed and the investigation is ongoing.
Whelan holds citizenship from U.S., Britain, Ireland and Canada, and Lavrov said Russia will allow consular visits.
Speaking on other issues, Lavrov insisted that Moscow isn't taking any sides in the controversy over Britain's exit from the European Union. He rejected allegations that Russia was gloating in the turmoil, saying that Russia is interested in seeing a "united, strong and, most importantly, independent European Union."
Commenting on the situation in Syria, Lavrov said that Moscow expects the Syrian government to take over territory in the country's east following the planned U.S. military withdrawal.
Jim Heintz in Moscow contributed to this story.
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