OTTAWA - The $3.4-billion purchase of four huge Boing C-17 military transport planes will scatter spinoff benefits across the country, but the Conservative government wouldn't say Friday which regions of Canada will get the biggest slice.

Defence Minister Gordon O'Connor, Public Works Minister Michel Fortier and Industry Minister Maxime Bernier, said the regional industrial benefits from the contract will bolster aerospace firms across the country.

Bernier said Boeing will announce specific contracts at a later date, which will help clarify where some some $577 million in spinoffs will land.

Earlier reports suggest Quebec companies are expected to see about 40 per cent of the money, but the government would not touch the subject Friday.

The first of the aircraft is expected to be delivered in the "August-September'' period, said O'Connor, with a second before the end of this year and two more in 2008.

"Gone are the days when we had to rely solely on our allies or commercial companies for airlift to respond to crisis situations,'' said O'Connor.

"Gone are the days when the Canadian Forces had to wait for years to get equipment they need for their jobs today.''

The first aircraft to be delivered is currently being built as part of a U.S. Air Force contract, but the American military has agreed to permit Canada to "step into the assembly line,'' said O'Connor, in order to get the plane more quickly.

The purchase of the strategic airlifters fulfils a promise the Conservatives made in the last election campaign.

Prime Minister Stephen Harper promised the planes in December 2005, saying they would give the Canadian Forces the ability to haul heavy loads, including the disaster assistance relief team, to distant locations without having to lease aircraft or beg a ride with allies.

"To be truly sovereign, we must be able to deploy our forces and equipment where they are needed, when they are needed,'' Harper said at the time.

"To put it bluntly, hitchhikers may get to their destination, but they don't get to pick the route or the timing.''

Opposition politicians complained that the purchase was made without the usual tendering process, but the government countered by saying the plane is unique and no other aircraft can duplicate it.

The C-17, which first flew in 1991, is widely used by the United States air force. Britain's Royal Air Force has four and plans to buy another and Australia took delivery of the first of four planes last December.

The planes are big -- 53 metres long with a 52-metre wingspan -- and can haul as much as 76 tonnes. They can be refueled in flight, giving them virtually unlimited range.

Despite their size, they can operate from runways as short as 1,100 metres.

The Conservatives are also in the process of seeking replacements for the aging fleet of C-130 Hercules transport planes, which have been the workhorse of the air force for decades, but which are rapidly coming to the end of the service lives.