OTTAWA -- The Canadian Forces says it is retiring two of the six Challenger executive jets it uses to transport VIPs.

It is estimated the move will save $1.5 million a year.

A statement from the Department of National Defence says the savings will be directed to operational needs, such as search and rescue.

In November 2012, the department said it would get rid of four of the planes, but that didn't happen.

Use of the twin-engine jets to ferry around politicians and officials has drawn political fire from opposition parties for years.

The Harper government says it uses the jets less than its Liberal predecessors, but just last March Prime Minister Stephen Harper was under fire for using a Challenger to attend Conservative party events.

The fleet is aging and the department has said four of the jets are at the end of their service life.

The electronic systems in these planes, known as CL600 and CL601 variants, are so old that their analog systems prevent them from flying overseas, said National Defence documents obtained last month.

Spare parts are also becoming an issue for the 30-year-old planes.