MANILA, May 6 (Reuters) - Nickel miner Agata Mining Ventures Inc (AMVI), partly owned by Canada's TVI Pacific Inc, has cancelled three of four ore shipments due to be exported in May from its mine in the Philippines, TVI said, citing depressed prices and low demand.

The Southeast Asian country was the biggest supplier of ore in 2014 to Chinese producers of nickel pig iron, used in stainless steel production, following a move by Indonesia to halt exports of unprocessed ore.

The boost in Philippine supply punctured a more than 50 percent rally in London Metal Exchange (LME) nickel prices , sending prices to six-year lows last month, although prices have since pared losses due to a weaker dollar.

"While AMVI has made great strides in ramping up production capacity in the last few months, the extreme volatility in Philippine nickel laterite prices has necessitated a high level of flexibility in our operations," TVI Chairman and CEO Clifford James said in a regulatory filing.

TVI did not disclose the total volume for the three cancelled shipments. Agata supplies ore to processing plants in Australia, China, South Korea and Japan.

Earlier this year it said ore shipments from Agata's mine in Surigao province in southern Philippines in 2015 would likely be more than 2.5 million wet metric tonnes.

Agata, which is also partly owned by TVI's local affiliate, TVI Resource Development, has so far exported 641,361 WMT of limonite ore and 60,369 WMT of saprolite ore this year.

"AMVI is closely monitoring market conditions and will continue adjusting its shipment schedule as necessary to ensure continued operational profitability," TVI said.

TVI Resource Development may push back a planned initial public offering to next year if metal prices remain depressed, James said last month.

(Reporting by Erik dela Cruz; Editing by Richard Pullin)