Libya military takes power plant near IS bastion Sirte
Fighters allied with the unity government "control all the thermal power plant" around 23 kilometres (14 miles) west of Sirte, a statement from the pro-government forces said.
The capture of the strategic plant follows the taking of two coastal towns earlier this week from the militants as forces advance towards Sirte, 450 kilometres east of the capital.
"Fighting resumed (on Wednesday) on the outskirts of Sirte between our forces" and IS, the statement said, adding that three pro-government troops had been killed and 10 more wounded in clashes.
Sirte was the hometown of slain dictator Muammar Gaddafi and, since seizing it in June last year, IS has turned it into a recruitment and training camp.
Western governments fear the militants could use Sirte's port and airport as a springboard for attacks in Europe.
But they have called for any offensive against the IS stronghold to be carried out under the auspices of the unity government installed in Tripoli since March 30 for fear that rival operations could play into the militant's hands.
The unity government has gradually asserted its control over key state institutions, but it still faces a rival administration with its own army in the east.