NEW DELHI — India will need to explore fresh options, including direct purchase, to shore up its air transport fleet as the Ukraine conflict has stymied the upgrade of its AN-32 aircraft, an Indian Air Force official said.

The last five of 40 AN-32 aircraft being upgraded in Ukraine have become "untraceable," the official said, and the local upgrade of the remaining 64 AN-32s has halted as Ukraine engineers departed and supplies of spares stopped.

"As AN-32 formed the bulk of the medium-lift segment of the transport fleet, urgent replacement of the Avro fleet, finalization of the joint development of medium transport aircraft and possible fresh purchases are some of the options which IAF will need to work on an urgent basis," retired Air Force wing commander Bhim Singh said.

In addition to the AN-32, the Air Force uses the Russian-made IL-76, British-made Avro, which is license-produced by Hindustan Aeronautics, and the US-made C-17 and C-130J Super Hercules.

In 2009, India contracted with Ukraine's state-owned arms trading agency, Ukrspetsexport Corp., to upgrade its 104 AN-32 transport aircraft at a cost of US $400 million as the fleet had reached its life expectancy. The program, which was to run through 2017, involved the upgrade of 40 aircraft in Ukraine and 64 under technology transfer from Ukraine at the Air Force's Kanpur-based base repair depot.

However, only 35 aircraft, upgraded at Kiev-based Antonov State Co. facilities in Ukraine, have returned, while the last five remain stranded due to the conflict.

"These five aircraft are almost lost as it is difficult to trace them and diplomatic efforts to find their whereabouts have failed," the Air Force official said.

A diplomat from the Ukraine Embassy said Antonov must resolve this issue with the Indian Air Force, and that the government cannot help. Antonov officials were unavailable for comment.

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The local upgrade at the Kanpur depot, which began three years ago, halted last year. Six aircraft were put for upgrade but work had to be discontinued as the Ukraine engineers left and only one container of spares from Ukraine had arrived, the Air Force official said.

The upgrade of the AN -32 would have extended the aircraft's life by 40 years with improved avionics, modernization of the cockpit and payload capacity being increased from 6.7 to 7.5 tons.

The AN-32 upgrade also includes spares from Honeywell and some Russian supplies.

"IAF had all along been maintaining that the local upgrade includes indigenization of spares and parts, and that most of them have been executed. With the local upgrade halted, these claims has been proven false," Singh said.

With the Indian government emphasizing strategic lift for internal deployment and the rushing of troops to the Chinese and Pakistani borders, additional transport aircraft are needed, Singh said.

AVRO Replacement

The status of replacing the Air Force's 56 Avro transports is unclear as only Airbus Defense and Space of Spain, which proposed the C-295 in a tie up with India's Tata Advanced Systems, has bid for the $3.5 billion tender, which closed late last year.

Ukraine's Antonov did not file a bid because the Defence Ministry refused to give it an extension.

With only one bidder, the tender faces cancellation.

Meanwhile, India and Russia propose to jointly develop a medium-lift transport plane capable of ferrying 80 troops together with infantry fighting vehicles or light tanks, artillery guns and ammunition, aimed at replacing the AN-32 fleet.