WASHINGTON (Reuters) - Republican White House candidate and champion for smaller government Ron Paul appears to have been reimbursed twice for travel between his congressional district and Washington with both taxpayer and campaign funds, the Roll Call newspaper said on Monday.

The libertarian congressman from Texas has staked his presidential campaign on a vow to slash government spending, but allegations that he may have received thousands of dollars in excess payments could taint his image and hurt his campaign for the Republican Party's nomination to face President Barack Obama in November.

Paul's office was not immediately available to comment.

The congressman has yet to win a nominating contest and is considered to have little chance to capture the Republican nomination.

Paul appeared to be reimbursed twice for eight flights between 1999 and 2004, according to copies of credit card statements obtained by Roll Call, campaign records filed with the Federal Election Commission and a quarterly expenditure disclosure. A Roll Call journalist who reported the story said Paul was paid an extra $4,422 from reimbursements for the eight flights which totaled $8,845.

Candidates must submit records of how they spend campaign donations to the elections commission and itemize any expenses above $500. Members of Congress have to file receipts for their expenses to the House of Representatives.

The documents showed that pro-Paul organizations like the Liberty Political Action Committee, the Foundation for Rational Economics and Education and the Liberty Committee sent checks to American Express paying for flights while Paul received payment from his congressional office for the same expenses, Roll Call said.

The commission could not comment on whether there were any investigations into Paul but said it had not received any complaints in reaction to the Roll Call story concerning Paul's use of campaign funds, an FEC official said.

In one instance in 2003, Paul bought a round-trip Continental Airlines flight between Washington and Houston worth $651.50 and appears to have been reimbursed by the Committee to Re-Elect Ron Paul and also his congressional office, Roll Call said.

(Reporting By Lily Kuo; Editing by Cynthia Osterman and Eric Beech)