PORTLAND, Ore. -- TriMet's board of directors approved Wednesday a 25-cent increase in fares for adults.

The fare increases, which are predominantly to offset rising fuel prices, will also include a 10-cent hike for youth, students, Honored Citizens and LIFT riders.

TriMet officials said that, although most of the increase was because of gas prices, 5 of the extra cents will be to offset general inflation.

Officials said that TriMet's fleet of vehicles has undergone adjustments to become one of the most fuel-efficient in the country, efforts that save more than $600,000 per year.

But even with those savings TriMet is paying more than $4.1 million more than it had budgeted for fuel.

After making fuel-efficiency improvements and cutting back on staff positions, the only way officials said they could fix budget problems was to increase fares.

Monthly passes for adult riders will go up by $10 making a two-zone pass that was previously $65 now $75 and a pass for all zones will rise from $76 to $86.

Monthly youth and student passes as well as those for Honored Citizens and LIFT riders will go up by $2 from $24 to $26.

In addition to these increases TriMet officials have decided to introduce new two-week passes that will give riders the savings of a monthly pass able to be bought in smaller increments.

The new rates go into effect Sept. 1.