WASHINGTON -- A whistleblower from the Department of Homeland Security who says he was pressured to suppress facts in intelligence reports says he won't be able to testify before a House panel until the department gives him more access to “relevant information,” according to his lawyer.

Attorney Mark Zaid said Brian Murphy, a former top intelligence official at the department, won't participate in a closed-door deposition with the House Intelligence Committee “until the clearance issues have been resolved favourably in order to properly protect Mr. Murphy's legal rights.” He says he and Murphy “look forward to and desire the opportunity” to participate.

“Mr. Murphy wishes to provide protected, classified whistleblower disclosures to the relevant oversight authorities in the Executive and Legislative Branches,” Zaid said in a statement. “That requires his access, as well as his legal counsel, to all relevant information.”

House Intelligence Committee Chairman Adam Schiff made Murphy's complaint public last week and said he had been invited to provide a deposition on Sept. 21. He has not been subpoenaed and was asked to participate voluntarily.

An intelligence committee official said the panel hasn't rescheduled the deposition at this time, but said DHS had delayed the processing of his lawyers' clearances. The official, who was granted anonymity to discuss the closed-door meeting, said the clearances were needed so Murphy could be properly represented during any classified portions of the deposition.

Murphy said in the complaint that he was pressured by senior officials to suppress facts in intelligence reports that President Donald Trump might find objectionable, including information about Russian interference in the election and the rising threat posed by white supremacists. The department has denied his allegations.

Murphy, a former FBI agent and Marine Corps veteran, also alleged that senior DHS officials pressed him to alter reports so they would reflect administration policy goals and that he was demoted from his post as principal deputy under secretary in the Office of Intelligence and Analysis for refusing to go along with the changes and for filing confidential internal complaints about the conduct. He remains with the department in a different capacity.