RICHMOND — Fresh off a sit-down with Syrian President Bashar al-Assad, Virginia state Sen. Richard H. Black turned up on an Arab TV channel last week making an extraordinary claim about one of the United States’ closest allies.

Black said Britain’s MI6 intelligence service was planning a chemical weapons attack on the Syrian people, which it would then blame on Assad.

“Around four weeks ago, we knew that British intelligence was working toward a chemical attack in order to blame the Syrian government, to hold Syria responsible,” Black said on Al Mayadeen, an Arab news channel based in Beirut.

Black (R-Loudoun) said later that he meant the British were planning not to carry out an attack themselves, but to either direct rebels to do so or stage a phony attack, with actors posing as victims.

Black also said some chemical attacks previously reported to have occurred in Syria were British fakes, pulled off with help from volunteer first responders known as White Helmets.

“From what I can tell, they have been planning a fake attack, not a genuine one, but one where they actually move people out of a town and they have trained people to portray victims of a gas attack,” Black said Friday in an interview with The Washington Post. “And the plan is to use the White Helmets who have always been involved in these notorious deceptions, to portray an attack.”

The State Department flatly rejected Black’s allegations, which echoed what it called “outrageous” Russian and Assad-regime claims that Britain and the United States have carried out chemical attacks with help from the White Helmets.

“The Syrian regime has repeatedly used chemical weapons,” a State Department official, who discussed the matter on the condition of anonymity because she was not authorized to do so publicly, said in an email. “Russian and regime denials have no credibility, nor does the increasingly offensive and outrageous Russian propaganda accusing the US and the UK of planning and executing CW attacks in order to justify retaliation in Syria. . . . The White Helmets are a humanitarian organization that has saved thousands of lives and continues to respond to bombardments by Russian and regime military forces.”

The British Embassy issued a statement Sunday calling Black’s allegations “nonsense.”

“Before Russia vetoed their UN Security Council mandate, international investigators found the Asad regime responsible for using chemical weapons four times,” the statement said. “The Asad regime’s use of these barbaric weapons against the Syrian people is beyond doubt. To suggest otherwise is nothing but propaganda by Russia and the Asad regime.”

His claims also drew condemnation from some Middle East experts.

“Wrap your head around this: an elected American official is parroting Russian/Assad Regime/Hezbollah propaganda on a TV channel closely affiliated with (if not under the direction of) a designated foreign terror org, Hezbollah,” tweeted David Daoud, a Washington-based research analyst at the think tank United Against Nuclear Iran.

Critics said Black was being used, perhaps unwittingly, as a tool for Syrian propaganda as government forces massed for an assault on Idlib province, the country’s last rebel-held stronghold. It is home to almost 3 million people, including hardened fighters who refused to surrender elsewhere. A least half of the population are civilians.

Black’s comments about Britain promised to draw more controversy to the 74-year-old legislator, who was interviewed Friday by the Russian state-owned RT TV network. Five Democrats are competing to take him on next year in elections that will determine whether Republicans hold on to their two-seat majority in the Senate.

This was Black’s second trip to visit Assad, whom the Trump and Obama administrations have blamed for chemical weapons attacks that have killed hundreds of civilians in rebel-held areas during Syria’s civil war. Black, a decorated Vietnam War veteran and retired Pentagon lawyer, regards Assad as a protector of Syrian Christians and a buffer against Islamist extremism.

“I’m just an individual who is deeply concerned about achieving peace and stopping the slaughter in the Middle East,” Black said. “Americans go all over the place all the time, and the only reason that they focus on me is because I tell the truth about what I’m seeing and what’s going on.”

Jake Rubenstein, spokesman for the Democratic Party of Virginia, called Black’s comments “a disturbing new low.”

“He is clearly more interested in being Bashar Al-Assad’s Propaganda Minister than a Virginia State Senator,” he said in an email.

Some Republicans expressed concern that Black’s controversial comments could hurt his chances for reelection and threaten the GOP’s efforts to hold Richmond’s upper chamber.

“He’s practically handing the majority to Democrats in the state Senate,” said former Republican delegate David Ramadan.

Others said Middle East politics are so complicated that voters may pay little attention. “People are never concerned about Dick Black going to Syria. People are more concerned about him coming back,” said Senate Minority Leader Richard L. Saslaw (D-Fairfax).

The state-run Syrian Arab News Agency identified Black as an “America senator” in reports on his visit. As a state legislator, Black plays no role in setting U.S. foreign policy. But he pushes back against the notion that the Syrian conflict does not affect Virginians, citing the U.S. troop presence in the Middle East, including troops from Virginia.

Black, who flew from Paris to Beirut and then traveled five hours by car to Damascus, said his flight and lodging outside of Syria were covered by Nasser Ani, a prominent surgeon from New Jersey who chairs the Syrian American Forum. The group has featured Black as a speaker.

Black said the Syrian government provided his lodging in Damascus, as well as an interpreter and ground transportation between Beirut and Damascus.

Virginia’s public officials cannot accept gifts worth more than $100 from lobbyists or government contractors. But Ani and the Syrian government do not fall into either category, so Black said their gifts are allowed.

State ethics officials signed off on Black’s 2016 trip to Syria, which carried a $10,000 tab that was paid by a Tampa-area gasoline wholesaler Paul Jallo. Black said last week’s trip cost far less because it was shorter.

Black said he and Assad spent three hours in the president’s office, in a mostly upbeat discussion about how the country has fared since the senator’s last visit.

“There was sort of a spring in his step and a sense of joy and optimism, and looking out to the future and bringing the nation together,” Black said.

Azhar AlFadl Miranda contributed to this report.