CHICAGO—McDonald’s said Thursday its french fries are now trans-fat-free in all its restaurants in the United States and Canada, catching it up with its fast-food rivals in that category.

CEO Jim Skinner made it official at its annual shareholders meeting at McDonald’s Corp. headquarters in Oak Brook, Ill.

McDonald’s has lagged other restaurant operators in switching over to a zero-trans-fat cooking oil out of worries it would compromise the taste of its trademark fries.

It has been under increasing pressure from consumer advocates and some public officials to make the change, but it did so quietly.

“For a few months now, customers in our U.S. restaurants have been enjoying our fried food items, including french fries, hash browns, chicken and filet of fish, as well as our biscuits, with zero grams of trans fat per labeled serving,” Skinner said.

There may still be negligible amounts of naturally occurring trans fats in the foods, but federal regulations allow foods to claim zero grams of trans fat as long as the levels are below 0.5 grams per serving.

Skinner said McDonald’s is on schedule to convert to the new oil by year’s end for its remaining baked items, pies and cookies.

“While we don’t plan to advertise these changes, we wanted you to be the first to know that we have followed through on our commitment while keeping the same great taste that our customers expect from McDonald’s,” Skinner said.

The $23 billion company was especially cautious in making the switch after reneging within months on a September 2002 pledge to introduce a new oil, citing the taste concerns.

McDonald’s has nearly 14,000 restaurants in the United States.

The company said it also has upheld its commitment to significantly reduce the amount of trans fat in its restaurants around the world, reducing it to less than 0.5 grams per serving in Europe, Latin America and its Asia Pacific-Middle East-Africa division. The four exceptions are Colombia, Japan, Ukraine and Venezuela, where McDonald’s is still working toward its reduction goals.

McDonald’s shares fell 25 cents to $58.53 Thursday.