WASHINGTON — Sen. John McCain's campaign is returning about $50,000 raised by a Florida oil executive because some of the funds were collected by a foreign national and came from donors who may not actually support the candidate, aides said yesterday.

"We thought it was an issue that there were people giving to the campaign who had no intention of supporting or voting for John McCain," said Brian Rogers, a campaign spokesman. "So we thought it was an appropriate measure at this point."

The decision to return the money follows a report in The Washington Post that found that Harry Sargeant III submitted a bundle of checks for $2,300 and $4,600 on a single day in March, all of it from donors in Southern California who had never given before this year's campaign and did not appear to be likely candidates to contribute as much as $18,400 per household.

Although the contributions were credited to Sargeant, whose company has Defense Department contracts worth up to $1.4 billion, the checks came from Americans of seemingly modest means.

Donors included the manager of Riverside-area Taco Bell restaurants, a couple who at one time ran a liquor store in Colton, and a Whittier auto mechanic.

Sargeant, who runs the International Oil Trading Co., in Boca Raton, Fla., said he asked several friends and colleagues to gather the funds for McCain. He had done the same for Sen. Hillary Rodham Clinton and former New York mayor Rudolph Giuliani during the primaries.

Sargeant said in an interview yesterday that he at times left the task of collecting the checks to a longtime business partner, Mustafa Abu Naba'a, who is not an American citizen. According to court records, Abu Naba'a is a dual citizen of Jordan and the Dominican Republic.

Money raised by Abu Naba'a is being returned. Sargeant raised at least an additional $460,000 for McCain. Some of that money was gathered on his behalf by a former high-ranking CIA anti-terrorism expert who is now Sargeant's business partner.

Rogers said the campaign wrote to donors whose checks Sargeant bundled, "reminding them of the campaign finance law and providing some information as to how to get a refund if that's what they desire."

It is illegal for a foreign national to donate to an American political campaign, but election law expert Fred Wertheimer said yesterday it is unclear whether a foreigner can solicit or bundle checks for a candidate.