Sri Lanka has made a formal request to the International Monetary Fund bailout package to aid its economy after a sharp slowdown in growth and with its budget deficit widening.

The IMF confirmed the island nation had asked for assistance.

Sri Lanka enjoyed a blistering economic growth rate averaging more than 8.0 percent for two years after a prolonged civil war ended in 2009.

But the pace of expansion has since slowed, falling to 4.8 per cent in the third quarter of 2015.

The IMF, which sent a mission this week to review Sri Lanka's economy, said it had warned the authorities they should make a "stronger effort" to immediately reduce the budget deficit.