CARACAS,  (Reuters) – Declared “persona non grata”  by the United States nine months ago, Venezuelan President Hugo  Chavez’s envoy returned to Washington yesterday, calling for  more oil cooperation and the extradition of an ex-CIA agent.

The United States is also sending its Ambassador Patrick  Duddy back to Caracas this week, ending a tit-for-tat  diplomatic spat that started when Chavez expelled him last year

The thaw with one of the United States most important oil  suppliers is an example of U.S. President Barack Obama’s policy  of engaging old foes.

Ambassador Bernardo Alvarez said his return was a historic  first step towards better relations and called for closer  cooperation on energy issues including improving oil-refining  capacity. “There has undoubtedly been a change,” Alvarez said in a  telephone interview with Reuters. “Finally the presidents took  the step.”

However, he said his government would continue to criticize  U.S. foreign policy and called for the extradition of Cuban exile  Luis Posada, a former CIA operative wanted in Venezuela for the  bombing of a Cuban airliner.

“We have rejected and will continue rejecting all these  attempts to unilaterally become the world’s judges, Alvarez said. “We want to keep insisting that for us, if you want to  fight against terrorism, the best way for the United States to  show that is to extradite to Venezuela Luis Posada.”