(Adds Freeport comment)
By Dennys Kapa and Michael Taylor
JAKARTA, March 20 (Reuters) - A blockade by workers at Freeport-McMoRan Inc's Indonesian mine extended into a fifth day on Friday, a union official said, with output still halted but maintenance workers allowed into the Grasberg site by protesters.
A lengthy disruption to supplies from one of the world's biggest copper mines could support benchmark metal prices that have dropped around 7 percent so far this year.
"The blockade is still happening today," Albar Sabang, a senior official at a Freeport union told Reuters on Friday. "The management is in dialogue with the protesters but we are not involved."
"Yesterday they allowed some technicians to go up to the mine site to take care of the machines," Sabang said about the demonstration, which relates to a settlement reached with other employees at the end of a previous dispute and is not union-backed.
The firm is working with the group of individuals involved in the demonstration to resolve their concerns, Freeport spokeswoman Ledy Simarmata told Reuters in an email on Friday.
Freeport Indonesia employs about 24,000 workers and is seen producing 43 percent more copper concentrate this year at 2 million tonnes.
Although copper ore production had been halted since Monday, stockpiles of copper concentrates were ready for shipment at a port used by the U.S.-based miner, union officials added.
Around 50 people are involved in Friday's blockade, Sabang added, which is a similar number to Thursday but down from more than 300 workers that protested earlier in the week.
Relations between Freeport and the workers' unions have been strained in recent years. Late in 2014, a planned one-month strike following the death of four workers was cancelled at the 11th hour.
Phoenix-based Freeport, whose shares fell more than 5 percent to close at $17.26 on Thursday, resumed concentrate exports after a seven-month tax dispute with the Indonesian government last year.
(Additional reporting by Michael Taylor; Reporting by Dennys Kapa; Writing by Michael Taylor; Editing by Michael Perry)