Former Washington Teachers' Union president Barbara A. Bullock last year spent about $500 in union money to purchase a Mont Blanc pen that she then presented as a gift to Mayor Anthony A. Williams, according to a city official and other sources.

The pen is being stored in the mayor's office, in its original packaging, and has not been used, said mayoral spokesman Tony Bullock, adding that he was unsure of the occasion that prompted the gift.

The union also provided Williams a desk clock encased in plastic, according to a disclosure report filed last year with the city's Office of Campaign Finance. The clock, an inexpensive item whose value could not be determined, was identical to ones distributed to union leaders at a meeting in Baltimore in 2001.

Federal authorities are investigating allegations that former union leaders, including Barbara Bullock, misspent millions of dollars. Two sources familiar with the case said the pen given by Bullock is thought to cost about $500 and is now part of the inquiry.

Tony Bullock said that if the gifts were purchased without proper authorization, the mayor likely will return them or refund the value. "The overriding point is that the mayor didn't ask for these items and doesn't really want or need these items," said the spokesman, who is not related to Barbara Bullock.

The spokesman said the mayor did not know, and did not ask, who paid for the pen or how much it cost. Williams has received hundreds of gifts since taking office in 1999, ranging from a red, gold-framed bow tie to amber cuff links.

Barbara Bullock, who did not return a telephone call, has not been charged. Her former chauffeur, Leroy Holmes, pleaded guilty last week to a money-laundering charge. No other charges have been filed, and officials said the investigation is continuing.

The federal investigation is also looking into how union money was spent on behalf of the mayor and his staff. Among the expenditures under investigation is a $20,000 bill to cater a party in 2001 for the mayor's chief of staff, Kelvin J. Robinson, sources familiar with the inquiry have said.

In addition, the city's Office of Campaign Finance is investigating allegations that the Williams campaign failed to itemize the costs of fundraisers hosted by Curtis Lewis, a lawyer who worked for the union and for the city. The campaign office also is looking into whether work done for the Williams campaign by Gwendolyn Hemphill -- Barbara Bullock's former assistant and co-chair of the mayor's reelection campaign -- amounted to an illegal in-kind contribution.

Also under investigation is an allegation from Hemphill that Robinson asked her to use union money to pay a bill of about $1,200 for T-shirts and other items from the 2000 Democratic National Convention. Robinson has said he expected Hemphill to use campaign funds.

In another development yesterday, four teachers sued the American Federation of Teachers, Independence Federal Savings Bank and several former union managers. The suit, filed in U.S. District Court, asks a judge to certify it as a class-action case so it will cover all of the union's 5,000 members.

The AFT, the union's parent organization, is being sued for not having required audits, and Independence Federal, where hundreds of false checks were apparently cashed, is being sued for being "grossly negligent." The AFT has said it was not responsible for closely overseeing the local union, and bank officials have declined to discuss specifics of the case.

Staff writers Allan Lengel and Neely Tucker contributed to this report.

Spending by former teachers union president Barbara A. Bullock is the focus of a federal investigation.