New Delhi: The Indian Air Force is all set to enhance the effectiveness of its medium-lift helicopter fleet by ordering additional 59 Mi-17-IV troop carriers from Russia which will replace ageing units of the same kind in the IAF's inventory. This versatile rotorcraft can also be configured in the gunship mode.

This order for 59 units is over and above the 80 ordered in December 2008. The earlier order for 80 was settled for $662 million. Going by that figure the fresh order should be somewhere in the region of $500 million.

While the previous order from 2008 was intended to enhance the numbers of the IAF's medium lift fleet, the fresh order will be used to replace older units as and when they are phased out in the coming years, defence ministry officials said here.

The new order has already been cleared by the Defence Acquisition Council and will now be forwarded to the Cabinet Committee on Security for clearance. This is expected to happen soon.

The first deliveries from the 2008 order are expected to be made by the end of this year. The remaining choppers will be phased in over a four-year period extending to 2014.

The Mi-17 is particularly useful in carrying out missions in high-altitude areas and in civil relief operations. It has a five tonne payload and apart from ferrying troops and VIPs can also be configured in the gunship mode. It was designed by the erstwhile Soviet Union for use in the Afghanistan War in the 1980s.