UPDATE 3-Over 30 dead in worsening Peruvian Amazon clashes

* Protesters, police dispute who shot first at roadblock

* Indigenous leader calls killings genocide

* Protesters dig in, taking 38 police as hostages

* Threat to torch Petroperu pumping plant (Recasts, adds police hostage)

By Terry Wade and Marco Aquino

LIMA, June 5 (Reuters) - Up to 31 people died and dozens were injured in clashes on Friday between Peruvian police and Amazon tribes protesting against government efforts to lure foreign energy and mining companies to the rain forest.

In the worst unrest to hit President Alan Garcia's current government, 22 protesters and nine police officers died, tribal leaders and the interior ministry said.

Angry protesters responded by saying they had taken a group of police hostage near an oil pumping station belonging to state-owned Petroperu. They threatened to set it ablaze unless police called off efforts to break up demonstrations in the Amazon basin.

"We have taken 38 police hostage," Carlos Huaman, a protester, said on RPP radio. "There are 2,000 of us and we are ready to burn the station."