The U.S. Secret Service on Sunday denied a suggestion from President Donald Trump's personal lawyer that it had vetted a meeting between the president's son and Russian nationals during the 2016 campaign.

Donald Trump Jr. has acknowledged that he met in New York with Russian lawyer Natalia Veselnitskaya after he was told she might have damaging information about his father's rival, Democrat Hillary Clinton.

"Well, I wonder why the Secret Service, if this was nefarious, why the Secret Service allowed these people in. The president had Secret Service protection at that point, and that raised a question with me," Jay Sekulow, a member of the president's legal team, said on Sunday on the ABC news program "This Week."

In an emailed response to questions about Sekulow's comments, Secret Service spokesman Mason Brayman said the younger Trump was not under Secret Service protection at the time of the meeting, which included Trump's son and two senior campaign officials.

"Donald Trump, Jr. was not a protectee of the USSS in June, 2016. Thus we would not have screened anyone he was meeting with at that time," the statement said.

According to emails released by Trump Jr. last week, he eagerly agreed to meet Veselnitskaya, who he was told was a Russian government lawyer. Veselnitskaya has said she is a private lawyer and denies having Kremlin ties.

On Friday, NBC News reported that a lobbyist who was once a Soviet counter-intelligence officer participated in the meeting, which was also attended by Trump's son-in-law, Jared Kushner, and the president's former campaign manager, Paul Manafort.

The meeting appears to be the most tangible evidence of a connection between Trump's election campaign and Russia, a subject that has prompted investigations by congressional committees and a federal special counsel.

Moscow has denied any interference and the president and Trump Jr. have denied any collusion.

Sekulow's comments about the Secret Service drew quick criticism, including from Frances Townsend, who advised former Republican President George W. Bush on homeland security.

"Ok let's try to deflect blame & throw those in @SecretService who protect @POTUS @realDonaldTrump @FLOTUS & family under the bus," she said on Twitter.

@FranTownsend Ok let's try to deflect blame & throw those in @SecretService who protect @POTUS @realDonaldTrump @FLOTUS & family under the bus

The Secret Service's mission is to provide physical protection for the U.S. president. The agency also protects major presidential candidates. But its role in vetting people who meet with a U.S. president or candidates is limited to ensuring physical safety.