The AC Transit Board on Wednesday approved labor contracts with two unions that lower district costs by having employees pay more for benefits and forego pay increases.

Operators of the financially struggling bus system estimate the district will save about $6 million over the life of the two contracts, one for 42 months and the other for 27 months.

Both deals require workers to start paying 10 percent of their premiums for medical and dental insurance.

The agreement with Local 1245 of the International Brotherhood of Electric workers gives 25 workers no pay increase from July 1, 2010, through Dec. 31, 2013.

The agreement with nearly 200 clerical, managerial and other workers includes a 5 percent pay cut in the first year of a 27-month agreement valid through September 2013. Wages will be restored in July 2013, according to a summary of the pact with Local 3916 of the American Federation of County, State and Municipal Employees.