By Emily Le Coz

JACKSON, Mississippi (Reuters) - A federal judge on Wednesday extended a temporary restraining order blocking Mississippi from enforcing a new state law that tightens requirements on abortion clinics, saying he wanted time to review how the law will be applied.

The new law, which took effect on July 1, has threatened to close the state's last abortion clinic and make Mississippi the only U.S. state without such a facility.

Abortion rights advocates say it is a thinly veiled attempt to ban the procedure in Mississippi. Supporters of the measure argue it is necessary to ensure women's safety.

Representatives for the state's lone abortion clinic, Jackson Women's Health Organization, asked U.S. District Judge Daniel P. Jordan III to issue a preliminary injunction to prevent the state from enforcing the law while its constitutionality is being challenged.

Jordan did not rule on that request at a hearing in Jackson, Mississippi on Wednesday. The judge extended a restraining order he issued on July 1 and said he would review the state Board of Health's new rules dictating how it would carry out the law at the center of the dispute.

The extension of the restraining order means the clinic can continue providing abortions for now.

The law, signed by Republican Governor Phil Bryant in April, requires physicians who perform abortions to be board-certified in obstetrics and gynecology, and to have admitting privileges at a nearby hospital.

Doctors at the Jackson Women's Health Organization already are certified OB-GYNs, but they haven't yet been able to obtain hospital privileges.

Clinic spokeswoman Betty Thompson said local hospitals - some of which are religiously affiliated - face tremendous pressure in the socially conservative state not to grant privileges to doctors who perform abortions.

CONSTITUTIONAL VIOLATION?

If Jordan eventually allows the state to begin enforcing the law, the clinic will be given some time to comply before facing license revocation. It would then be allowed to stay open while it appealed any such revocation, a process that takes at least 60 days.

The Jackson Women's Health Organization argued in court documents filed ahead of the hearing that the law "is motivated by a desire to close down the clinic and end abortion in the state, in defiance of the Constitution and with a disregard for the rights of individuals."

The state said the measure protects women's health by ensuring doctors have the credentials necessary to perform the procedures and access to hospitals in case of complications, court documents show.

The state also said it had "substantial reason for concern" about the health and safety record of the Jackson clinic, noting that another abortion clinic run by owner Diane Derzis had its license revoked by Alabama health officials in April after "multiple and serious violations."

The Jackson Women's Health Organization said it was found to be in compliance with all applicable Mississippi laws after its most recent inspection in June, according to court documents.

Mississippi, which had as many as 14 abortion providers in the early 1980s, already has some of the country's strictest abortion laws and one of the lowest abortion rates. It also has the highest teen pregnancy rate in the United States - more than 60 percent above the national average in 2010.

Thirty-nine other states say that only OB-GYNs can perform abortions, and nine others mandate hospital privileges, according to the Guttmacher Institute, a nonprofit organization focusing on sexual and reproductive rights.

The Jackson Women's Health Organization opened in Mississippi in 1996. Thompson said about 2,000 women received abortions at the clinic between July 1, 2010 and June 30, 2011.

(Editing by Colleen Jenkins and Greg McCune)