By David Beasley

ATLANTA (Reuters) - The FBI says it is investigating "intentional" fires that erupted this week at two Atlanta-area women's clinics, one of which performs abortions.

"FBI-Atlanta is seeking information regarding intentional fires," the agency said in a statement.

It said the first of the blazes occurred on Sunday morning after someone broke out the front window of a gynecological office and set a fire inside the building.

"An incendiary substance was present," the FBI said in its statement. "Laboratory results are pending."

On its website, the doctor's office told patients that "the office sustained severe damage."

On Wednesday, a second fire broke out at a suburban Atlanta abortion clinic, the FBI said.

It took about 20 minutes to get the second fire under control, Cobb County Fire Department spokeswoman Denell Boyd said on Friday. There were patients inside the clinic when the fire erupted, but they were on a different floor of the building and no one was injured.

Georgia Right to Life, which opposes abortion, said in a statement that it "categorically condemns violence of any kind. Such actions are abhorrent and have no place in a civil society."

Earlier this year, there were burglaries at the headquarters of the Georgia Obstetric and Gynecological Society and two OB/GYN offices in Atlanta, said Pat Cota, the society's executive director. Laptop computers were stolen, she said.

The doctor's office damaged in Sunday's fire was one of the two offices burglarized earlier in the year, Cota added.

"It's bizarre," Cota said on Friday of the burglaries and fires. "We just wish it would stop."

She did not elaborate, but Georgia recently passed legislation outlawing most abortions after 20 weeks of pregnancy.

(Editing by Tom Brown and Vicki Allen)