Trump can ask the full DC Circuit to reconsider the three-judge panel's decision

A federal appeals court on Friday rejected US President Donald Trump's bid to block the release of years of his financial records, inflicting the latest setback in his effort to stop House Democrats gathering evidence for their impeachment inquiry.

In a 2-1 ruling, the US Court of Appeals for the DC Circuit rejected Trump's argument that the House Oversight Committee lacked the authority to issue a subpoena to the president's longtime accounting firm, Mazars.

The decision marked a major victory for Democrats leading wide-ranging congressional investigations into the president's business affairs after he reneged on a campaign promise to release his tax returns.

Democrats are investigating whether Trump inflated the value of assets to obtain loans and in April subpoenaed "statements of financial condition, annual statements, periodic financial reports, and independent auditors' reports prepared, compiled, reviewed or audited by Mazars."

Trump can ask the full DC Circuit to reconsider the three-judge panel's decision, or go straight to the Supreme Court to look at the case.

The White House, which has characterized congressional investigations into the president as "harassment," argued that Congress did not need the information to fulfill its role as legislator.

That stance was dismissed by a Washington judge in May.

"The district court granted summary judgment in favor of the committee, and we affirm," wrote Judge David Tatel in his judgment.

"Contrary to the president's arguments, the committee possesses authority under both the House rules and the constitution to issue the subpoena, and Mazars must comply."

After taking control of the House in January, the Democrats launched numerous investigations into Trump's finances and accusations that he obstructed a federal investigation into his campaign's involvement in Russian interference in the 2016 election.

The White House has stonewalled requests for documents and witnesses, citing "executive privilege."

A federal judge on Monday dismissed Trump's bid to block access to years of his personal and corporate tax returns, saying sitting presidents are not immune from criminal investigations.

Lawyers for Trump immediately appealed to the US Court of Appeals for the Second Circuit, which issued a temporary stay of the judge's order.

The battle has escalated since the Democrats announced an impeachment probe on September 24, accusing the president of having betrayed his oath of office by lobbying Ukraine to help him smear a political rival.

Democrats have since issued subpoenas targeting the State Department, Energy Secretary Rick Perry and Trump's personal lawyer Rudy Giuliani.

The White House said in an eight page letter Tuesday that it was withholding cooperation with the probe, denouncing it as "partisan and unconstitutional."