WASHINGTON (AP) — The White House says world powers negotiating with Iran are pursuing an agreement that would offer some sanctions relief if Iran halts and possibly reverses parts of its nuclear program.

White House spokesman Jay Carney says the first step would deal with Iran's most advanced nuclear activities. The goals would be to increase transparency and create more time for further negotiations.

Carney says in exchange, the world powers would consider targeted and limited sanctions relief. He says the relief would be reversible, and sanctions could even be ratcheted up, if Iran breaks its word.

Talks resumed Thursday between Iran and the U.S. and five world powers. Iran's chief negotiator says those countries have accepted Iran's plan. Carney wouldn't comment on timing for reaching a deal.