NORWALK, Conn. (AP) _ An animal rights activist was arrested today on charges she planted a pipe bomb in an attempt to kill the chairman of a surgical equipment company that experiments on dogs, police said.

Police said 33-year-old Fran Stephanie Trutt of New Hyde Park, N.Y., was arrested setting the radio-controlled bomb at U.S. Surgical Corp. just after midnight.

She was charged with attempted murder, possession of explosives and manufacturing a bomb and was jailed on $500,000 bail.

Lt. Jeff Finch said the device was a ''sophisticated bomb capable of killing anyone near it.'' Ms. Trutt planned to detonate it as the company's chairman, Leon Hirsch, walked by on his way to work, Finch said.

''Ms. Trutt is a self-styled member of animal rights groups and considers the policies of U.S. Surgical to be an affront to animal rights,'' Finch said.

Hirsch said the bomb was found at the side of the building, 10 feet from his parking space. He said about 200 people were working in the plant overnight. A bomb squad was called in to remove the device.

The company has been criticized for using anesthetized live dogs to demonstrate its surgical staplers, which are used instead of stitches to close wounds.

State health officials, responding to complaints by animal rights groups, ruled recently that such use of animals does not violate state law.

''I think what we and other companies should be doing is telling the world what these animal activists are really like,'' Hirsch said. ''The public thinks they're a wonderful group of little old ladies, protecting puppies and pound dogs, and so they send in their $5.''

''But nothing could be further from the truth. These are hard-core animal extremists, who believe the rights of animals supercede the rights of humans.''

An animal rights activist who protested U.S. Surgical's use of animals to the state said the group has ''absolutely no connection'' with Trutt.

''We were horrified to learn of this,'' said Julie Lewin, Connecticut coordinator of Fund for Animals, which claims 250,000 members nationwide. ''We in no way condone any terorrism. Violence toward people does not help animals.''

Hirsch said U.S. Surgical experiments on about 1,000 animals, mostly dogs, a year. The animals, which are obtained from U.S. Department of Agriculture farms, are destroyed after experiments are completed, he said.

U.S. Surgical, which produces surgical stapling devices, employs 1,500 people in Connecticut and 2,600 nationwide, Hirsch said.