Washington, Aug 14 (DPA): US regulators have approved an emergency contraceptive that can prevent pregnancy when taken within five days of unprotected sex, but which has drawn ire from anti-abortion advocates.

The Food and Drug Administration approved Friday the medication ulipristal acetate, known by the brand name ella, for use in the US.

It is effective much longer than other emergency contraceptives available in the market, which are ineffective after three days. It prevents pregnancy by delaying or inhibiting ovulation in women and was found to be safe in clinical trials, the FDA said in a statement.

Though the pill has been available in Europe for a year, it had generated controversy in the US where some anti-abortion groups have said it is closer to an abortion pill than a contraceptive.

They argue labelling the product a contraceptive is misleading because it could cause an abortion and is similar to abortion drug RU-486.

The FDA's irresponsible approval of ella (Ulipristal), without adequate safety studies, places women's health and lives at risk," said Dr Charmaine Yoest, head of Americans United for Life. "Furthermore, billing this abortion-causing drug as an 'emergency contraceptive' is misleading to the public."

However, the move was welcomed by pro-choice advocates.

"Every woman deserves every option available to prevent an unplanned pregnancy, and there are many reasons why a woman may face the risk of unintended pregnancy from failure or improper use of birth control, to sexual assault," said Cecile Richards, president of Planned Parenthood Federation of America.

"The FDA's approval of this new form of emergency contraception gives women one more option."