HARRISBURG — Former state Sen. Robert Mellow paid a $21,000 fine for billing taxpayers to cover rental space for his district office in a building that he and his wife had a financial interest in, the State Ethics Commission said.

Mellow, 69, a longtime Democratic floor leader who retired in 2010, was fined as part of a consent agreement settling allegations that he had violated the state ethics law ban on public officials using their office for the financial gain of themselves, immediate relatives or a family related business.

Meanwhile, he also is accused of misusing public resources for political purposes. That hearing was postponed Thursday.