The Reserve Bank of India headquarters in Mumba on April 8 | BLOOMBERG

Foreign-exchange reserves are slumping across Asia as policymakers shell out funds to defend their currencies against the spike in oil prices caused by the Iran war.

The Philippines has led losses with its stockpile sinking 8.1% since the conflict started to $104 billion, while India’s dropped 5.2% to $691 billion and Indonesia’s slipped 3.8% to $146 billion, data compiled by Bloomberg show. The declines represent both the drain from spending to support local currencies, and a reduction in the value of non-dollar holdings.

The slide in reserves adds to evidence that Asia has been one of the biggest losers from the Middle East conflict due to its reliance on energy imports.…