UPDATE 1-Puerto Rico oversight board asks court to enforce furloughs

(Adds details from lawsuit)

NEW YORK, Aug 28 (Reuters) - Puerto Rico's federal oversight board on Monday sued Governor Ricardo Rossello, saying he has no authority to reject planned employee furloughs and pension cuts it says are necessary to pull the U.S. territory from the brink of economic calamity.

Escalating a long-running power struggle between the federally-appointed board and the governor, the lawsuit asks a U.S. federal court in San Juan to rule the planned furloughs and pension cuts are part of an economic turnaround plan that has been approved by the board.

"The governor must enforce and comply with all aspects of the ... fiscal plan, including but not limited to the furlough program and the pension overhaul," the board said in a 23-page complaint.

Rossello's administration has said it will not impose furloughs or pension cuts, arguing they were not part of the original turnaround plan, but amendments added by the board.

Puerto Rico is struggling to regain economic stability in the face of a debt load of $72 billion, a 45 percent poverty rate, and near-insolvent public health and pension systems.

The American Federation of State, County and Municipal Employees (AFSCME) has filed a lawsuit seeking to halt the furloughs, slated to take effect on Thursday, while local unions have planned widespread protests on Wednesday against austerity measures pushed by both Rossello and the board.

(Reporting by Nick Brown; Editing by Cynthia Osterman and Paul Simao)