Amid recent scrutiny about his spending habits, the man in charge of the Smithsonian Institution has resigned, officials said Monday.

Secretary Lawrence M. Small, a former banker who was the first businessman to run the venerable museum complex, educational facility and research hub, resigned Sunday after more than seven years in the Smithsonian's top post.

"His long service and outstanding service were weighed against the current contrary feelings among some people in the community," said Roger Sant, chairman of the Smithsonian board's executive committee.

Sant added that biologist Cristian Samper, director of the Smithsonian National Museum of Natural History, will serve as acting secretary during the search for Small's replacement.

Like the Smithsonian's first nine secretaries, the Harvard-trained Samper comes from a scientific background.

In January, the results of an internal audit were made public and revealed that Small allegedly had racked up thousands of dollars in unauthorized expenses and received questionable compensation, including for holding official functions in his lavish Washington home and charging the Smithsonian for it.

Last week, the U.S. Senate withheld a proposed $17 million US funding increase to the Smithsonian, citing Small's excessive spending habits and compensation.

Small will not receive a severance package, Smithsonian officials said.

"Having spent countless days and evenings promoting the interest of the institution and having contributed over a half a million dollars of my own money as well, it has truly been a labor of love," Small said in a statement.

Praise and criticism

Though he was praised for his highly successful fundraising for the Smithsonian and for opening new museums during his seven-year tenure, Small also attracted his share of criticism over the years.

Early on, he had been criticized for imposing changes without the support of museum staff and for cutting research funding.

In 2004, he was sentenced to probation and community service after being convicted of importing South American artifacts featuring feathers from endangered birds for his personal collection.

Just last year, historians and filmmakers attacked Small for signing a semi-exclusive deal to create TV productions with Showtime Networks. Many felt that the deal would limit access to the Smithsonian's resources for other groups.

An investigation by the U.S. Government Accountability Office later concluded that the deal hasn't affected other filmmakers' access.

A recent independent review of the Smithsonian's eight art institutions also called for major renovations of the buildings, management and funding.

With files from the Associated Press