Donald Trump Jr. had denied participating in any campaign-related meetings with Russian nationals when he was interviewed by The Times in March. “Did I meet with people that were Russian? I’m sure, I’m sure I did,” he said. “But none that were set up. None that I can think of at the moment. And certainly none that I was representing the campaign in any way, shape or form.”

Asked at that time whether he had ever discussed government policies related to Russia, the younger Mr. Trump replied, “A hundred percent no.”

The Trump Tower meeting was not disclosed to government officials until recently, when Mr. Kushner, who is also a senior White House aide, filed a revised version of a form required to obtain a security clearance. The Times reported in April that he had failed to disclose any foreign contacts, including meetings with the Russian ambassador to the United States and the head of a Russian state bank. Failure to report such contacts can result in a loss of access to classified information and even, if information is knowingly falsified or concealed, in imprisonment.

Mr. Kushner’s advisers said at the time that the omissions were an error, and that he had immediately notified the F.B.I. that he would be revising the filing. They also said he had met with the Russians in his official transition capacity as a main point of contact for foreign officials.

In a statement on Saturday, Mr. Kushner’s lawyer, Jamie Gorelick, said: “He has since submitted this information, including that during the campaign and transition, he had over 100 calls or meetings with representatives of more than 20 countries, most of which were during transition. Mr. Kushner has submitted additional updates and included, out of an abundance of caution, this meeting with a Russian person, which he briefly attended at the request of his brother-in-law Donald Trump Jr. As Mr. Kushner has consistently stated, he is eager to cooperate and share what he knows.”

Mr. Kushner’s lawyers addressed questions about his disclosure but deferred to Donald Trump Jr. on questions about the meeting itself.