(Adds Kushner comments in television interview, paragraphs 9-10)

By Ginger Gibson and Mark Hosenball

WASHINGTON, April 1 (Reuters) - A White House whistleblower has said the Trump administration overruled security experts to give questionable security clearances to more than two dozen people, including the president's daughter Ivanka and son-in-law Jared Kushner.

Tricia Newbold, a White House security adviser, told Democrats in Congress that clearances were initially denied to dozens of administration officials because of concerns over possible foreign influence, conflicts of interests, questionable or criminal conduct, financial problems or drug abuse.

She said President Donald Trump's former White House personnel security director, Carl Kline, personally overruled the career officials' judgments in the cases of two senior officials.

Newbold's allegations were laid out in a letter sent to the White House on Monday and released by Elijah Cummings, chairman of the House of Representatives Oversight Committee.

"I would not be doing a service to myself, my country, or my children if I sat back knowing that the issues that we have could impact national security,” his letter quoted Newbold as telling his committee. "I feel that right now this is my last hope to really bring the integrity back into our office."

Cummings said he plans to subpoena Kline and warned that more subpoenas would be issued if the White House does not provide requested documents.

In his letter to the White House, Cummings referred to three unnamed "senior White House officials" whose security clearance cases are addressed in some detail by Newbold.

Two sources familiar with the information obtained by the Oversight Committee said two of those three senior officials are Ivanka Trump and Kushner, her husband.

Asked about the whistleblower's assertions, Kushner said in an interview on Fox News Channel that he had complied with various investigations.

"I disclosed all of my holdings for the Office of Government Ethics, and what I did with them is they told me what to divest, what to keep, what rules to follow. We followed all that," Kushner said.

The White House did not respond to a request for comment.

Jim Jordan, the top Republican on the House committee, issued a statement calling the letter a "partisan attack" that was "an excuse to go fishing through the personal files of dedicated public servants."

Cummings said Newbold, a manager in the White House personnel security office, said she was targeted for retaliation after declining to approve applications based on national security protocols.