OKLAHOMA CITY (Reuters) - Oklahoma Governor Mary Fallin on Wednesday signed into law a prohibition on abortion after 20 weeks of pregnancy, making it the fourth state to ban such late term abortions.

She also signed a law preventing health insurers from covering elective abortions.

Fallin, a Republican serving her first term, said both laws are important measures that safeguard life.

"Together, these two pieces of legislation will expand protections for unborn children and ensure that Oklahomans are not forced to unknowingly or unwillingly help to pay for procedures that run contrary to their values," she said.

Barbara Santee, former executive director of NARAL Pro-Choice America's Oklahoma office, called the two laws "a frontal assault" on the 1973 U.S. Supreme Court decision that legalized abortion.

"This is just chipping away at a woman's right to choose," she said.