New Delhi has suspended its planned acquisition six Airbus Defence & Space A330 multi-role tanker transport (MRTT) aircraft, creating uncertainty about its long-term air-to-air refuelling capability.

A source familiar with the matter says it is not clear exactly why the acquisition, originally announced in 2013, was suspended.

As recently as June, Airbus was confident that New Delhi would advance its deal for the type.

Media reports citing unnamed sources suggest that perceived costs related to the Airbus platform could be an issue. If true, this would mark the second time cost concerns have derailed New Delhi’s acquisition of the A330 MRTT, which has twice been selected to meet the country's tanker requirement.

In both competitions the twin-engined aircraft, based on the A330 commercial airliner, prevailed over the four-engined Ilyushin IL-78MK. Both competitions assessed aircraft life-cycle costs as an evaluation metric.

The news is a rare setback for the MRTT programme, which has enjoyed broad international success in recent years.

Flight Fleets Analyzer shows that there are 23 A330 MRTTs in service globally, with nine aircraft on firm order. India excluded, Airbus has letters of intent for 19 additional examples.

Operators include the air forces of the United Kingdom, Australia, Saudi Arabia, and the United Arab Emirates.

The type will also provide future tanking capability for air forces such as Singapore, South Korea, France, and Qatar.

More recently, a multinational initiative to acquire a pooled fleet of A330 multirole tanker/transports edged closer to take-off, with the Netherlands and Luxembourg agreeing to buy an initial two examples. This acquisition is the first part of a potentially broader activity being pursued by the European Defence Agency and several other nations.

Fleets Analyzer shows that India’s tanker fleet comprises seven IL-78Ms delivered in the 1990s.

Should India decide to relaunch its tender for new tankers, competitors are likely to again include the A330 MRTT and IL-78MK.

Boeing, which did not participate in India’s latest tanker competition, could also pitch its KC-46A, which is based on the 767 airliner.