SINGAPORE, March 11 (Reuters) - Singapore Airlines , the world's biggest airline by market value, has asked staff to take unpaid leave for up to two years in a bid to reduce costs.

The scheme, which is voluntary, applies to the carrier's 14,000 employees, the Straits Times newspaper said on Wednesday.

An SIA spokesman confirmed the report when contacted by Reuters.

The Singapore carrier, which last month announced plans to cut its capacity by 11 percent and has grounded 17 of its 100-plus aircraft, has already asked pilots at its cargo arm to volunteer for unpaid leave.

The carrier said last month its quarterly profit fell 43 percent, hurt by hedging losses and slowing demand for travel and cargo.