(Adds quotes from mining federation)

By Marco Aquino and Terry Wade

LIMA, Oct 21 (Reuters) - Peruvian mine workers returned to work on Wednesday after a 48-hour mining strike intended to pressure Congress to pass two bills that would improve labor benefits, the national association of mining unions said.

Miners want the government to lower the age for retirement and lift caps on profit-sharing, but it is not known when the bills might be put on the agenda for floor votes.

"If there's not political will to solve this issue we will resume the protest. We will have an emergency meeting Nov. 13 and 14 about this," said Luis Castillo, director of the union federation, told Reuters.

He threatened another strike in late November or early December if Congress fails to act.

Congressional staffers said there was a chance the bills could have been put to floor votes this week, but the Social Security Committee said the bill on early retirement still needs to be amended to reflect changes requested by President Alan Garcia.

The walkout came as mineral prices have gained ground and mining companies are expected to post higher third-quarter profits after a tough first half of the year. The national federation of mining unions has said it will plan an indefinite strike if it does not get what it wants now.

The Congressional Committee on the Economy approved both bills earlier this year and Congress as a whole later passed the retirement rule.

But it was vetoed by President Garcia, angering miners.

Early retirement for miners might require private pension funds to pay out millions of dollars in extra benefits.

Union leaders said the walkout hit mines of Buenaventura, Barrick and Volcan, while those of Southern Copper <SPC.LM><PCU.N>, Freeport <FCX.N>, BHP Billiton <BHP.AX> <BLT.L>, Xstrata <XTA.L> and Newmont <NEM.N> were spared. [ID:nN20438650]

Buenaventura <BVN.N> said on Wednesday that work had returned to normal at its mines.

Workers at Barrick's <ABX.TO> <ABX.N> Peruvian gold mines also had walked off the job during the strike, though a Barrick official reported output was not cut.

Volcan <VOL_pb.LM>, one of Peru's top zinc and silver producers, was similarly hit by the work stoppage, though a company official said production was not affected.

Peru ranks No. 1 in global silver output, No. 2 in zinc, No. 3 in copper and tin, No. 4 in lead and No. 6 in gold. (Reporting by Terry Wade and Marco Aquino; editing by Marguerita Choy)

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