The federal opposition has pleaded with the military wages tribunal to reject the government's below-inflation wage offer to the Australian Defence Force.

The call comes as political pressure builds on the Abbott government over its proposed pay deal Australia's sailors, soldiers and air force personnel.

Opposition Leader Bill Shorten and members of his frontbench joined a hastily organised grass roots campaign by military advocacy groups against the offer of 1.5 per cent per year and the loss of leave entitlements which was conveyed to troops on Friday.

With the Defence Force Remuneration Tribunal due to hear the government's case in Canberra on Wednesday, both the government and the system for determining military wages was coming under fire.

Labor was accusing the government of hypocrisy on Monday, pointing out that Assistant Minister of Defence Stuart Robert, while in Opposition in 2011, attacked a 3 per cent per year increase in military wages as "outrageous".

Mr Shorten wrote to Prime Minister Tony Abbott on Monday urging the Prime Minister to reconsider the offer and to the tribunal's president, Anne Harrison, asking her to reject the government's case on Wednesday.

"I am deeply disturbed at the inequity that seems apparent in the position of the government," Mr Shorten told the tribunal president.

"What is even more unconscionable is that this `offer' is to be offset and `funded' by a range of what are described as `productivity initiatives' which include removing some previously approved leave provisions and downgrading of several other conditions of service.

"Families of service members have been telling my office that these leave provisions are vital in helping them manage the enormous strain placed on families by the lengthy periods spouses are required to be absent from the home and the extra hours of service for which they receive no overtime or rostered days off."

Shadow defence minister Stephen Conroy and parliamentary secretary Gai Brodtmann were also on the attack on Monday after more than 11,000 service men and women and their families contacted the Defence Welfare Association, most of them expressing anger at the deal.

"Tony Abbott promised no surprises, and now he wants to cut the wages of our Defence personnel," Senator Conroy said.

"I mean, it's quite extraordinary: no surprises, send the troops to war and then suddenly cut their pay.

"You've seen the level of outrage in just a few days from the Defence forces themselves.

"The Defence forces are up in arms, but they don't have any other capacity than to talk to their welfare association and to make some public commentary."

The association's national president, Colonel David Jamison, said that, given the overwhelmingly negative response by service personnel to the proposed offer, it left  the association  no choice but to oppose it in its submission to the tribunal.

The only government figure out defending its stance on Monday was parliamentary secretary to the Treasurer Steve Ciobo who returned Labor's accusation of hypocrisy.

"The Australian Labor Party presided over the biggest deterioration in Defence Force spending in Australia since the Second World War," he said.

"The fact is Labor is big on rhetoric, big on talk.

"You're now demanding all this extra pay, and your opposition stands in contrast, and stands in opposition to us actually making additional budget savings which could pay for the very increases that you're talking about."

Australia Defence Association executive director Neil James was scathing about the deal on Monday and said the system for determining military wages was "crazy" and needed complete reform.

"They need to come up with a way that determines ADF pay, independent of the compromising position it puts the chief of the Defence Force in," Mr James  said.

"For example, he has to choose between buying new equipment to replace obsolescent equipment or giving the troops a pay rise.

"Pay should not be determined by those types of decisions."