Union ends strike at Buenaventura's Peru mines

* Workers walked out at 3 mines on Feb. 13

* Union leader says miners likely to strike again soon

LIMA Feb 20 (Reuters) - Workers who walked off their jobs last week at mines owned by Peru's largest precious metals miner, Buenaventura (BUEv.LM) (BVN.N), returned to work early on Saturday, although they are likely to strike again on March 3, a union leader said.

The stoppage, which began on Feb. 13, halted production at the Orcopampa gold mine and the Uchucchacua silver mine. It also crimped output at the Antapite gold mine, although the company had declined to say at what capacity the mine was operating during the strike.

The Labor Ministry had declared the walkout illegal, saying the union failed to meet formal legal requirements -- a move that gave Buenaventura leeway to start firing workers.

The ministry almost always declares miners' strikes illegal.

"We will strike again starting March 3," Luis Castillo, head of the country's largest federation of mine workers, told Reuters.

He said some 4,380 miners had participated in the strike, and decided to return to work to avoid losing their jobs.

Workers are seeking information about Buenaventura's finances between 2006 and 2009.

Mining companies in Peru must share 8 percent of their profits with employees, and miners say Buenaventura has underreported its earnings.

The company has said Peru's tax agency is reviewing its tax law compliance and that it expects a favorable outcome.

Castillo said workers' assemblies were planned for the next few days and if workers vote in favor of the strike again, the union could go out as early as March 3.

He was confident workers would vote to walk out.

Antapite produced 965,227 fine grams of gold last year, while Uchucchacua ground out 286,039 fine kg of silver and Orcopampa produced 8,549,730 fine grams of gold, according to the Mining Ministry.

Besides the mines it operates directly, Buenaventura holds minority stakes in two other Peruvian mines -- Yanacocha -- one of Latin America's largest gold mines, and Cerro Verde (CVE.LM), a major copper pit.

Globally, Peru ranks No. 1 in silver production and sixth in gold. (Reporting by Dana Ford; Editing by Peter Cooney)