* Economist Rivera replaces Viteri as finance minister
* Part of President Correa's wide cabinet reshuffle
The chief of Petroamazonas, Wilson Pastor, told Reuters he would be the next energy minister of the South American oil-exporter, which has the rotating presidency of OPEC.
The changes at the ministries are not expected to lead to major shifts in Correa's state-centric policies. They come as Ecuador's economy lags government growth forecasts, Correa's popularity softens and the Leftist leader loses patience with talks aimed at securing new contracts with private oil firms.
Viteri was replaced by 31-year-old Patricio Rivera, an economist with a state planning office.
"Lack of sufficient tenure at the head of the ministry of finance, which a key position, is a definite drawback to the cohesiveness of economic policy," said Alberto Bernal, head of research at Bulltick Capital Markets in Miami.
"Hopefully this new blood in the finance ministry will help president Correa come up with policies more in line with the marketplace. Ecuador is in dire need of financing and his policies so far have not helped attract investment," Bernal said.
The country has been cut off from the international capital markets since 2008, when it declared $3.2 billion in global bonds "illegitimate" and defaulted on the obligations.
Outgoing finance minister Viteri, like Correa a leftist economics professor, was unpopular with Wall Street for her central role in that default.
The cabinet reshuffle coincides with government threats to take over the operations of private petroleum companies unless they sign the new deals favoring the state.
The new contracts are to be aimed at ending profit-sharing deals with foreign companies and turning the firms into service providers.
Correa had already replaced nine ministers this month after telling the whole cabinet to submit resignation letters.
Incoming oil minister Pastor now takes over as head of OPEC. The position of OPEC chief is mostly symbolic and lacks significant policy-making weight.
Correa, a U.S.- and European-trained economist, took office in January 2007 and his popularity rating rose above 70 percent in his first years as he redistributed wealth to the poor and took a tough stance against foreign investors.
But his ratings have sunk below 50 percent since, largely because of a slow economy as the country's oil revenues were battered by the global economic slump and a fall in petroleum demand.