The Army's controversial assault rifle is not to be replaced despite complaints about performance, the Ministry of Defence is expected to announce.

The SA80 is the UK forces' standard weapon, but troops in Afghanistan had reported the rifle sometimes jams in action.

There had been reports the government was considering scrapping it but this option is thought to have been rejected.

Instead, the BBC has learned the MoD is now embarking on a confidence building exercise in the Omani desert, where the SA-80 is being tested against other weapons, including the American M-16.

The aim is to show that British soldiers are not being issued with inferior kit and sources have told the BBC there is no question of replacing the SA-80.

At the heart of the problem is a �92m upgrade of the rifle.

The original SA 80

In service since 1985 Made by Heckler and Koch (UK) Fires Nato standard 5.56 x 45mm ammo Weight 4.98kg Length 750mm Muzzle velocity 940m/s Effective range 500m Cyclic rate of fire 610/770 rounds/min *Stats from MoD

Tests are believed to have shown that, among troops using cleaning methods associated with the old version of the rifle, reliability was just 17%.

However, among those following a new maintenance regime, the figure was 85%.

The message the MoD is anxious to convey to its soldiers - look after your weapon properly, and it will look after you.

Upgrades

Defence Secretary Geoff Hoon has notably failed in the past to give the rifle his full backing and several senior MoD figures want to get rid of it.

A series of problems with the previous SA80 rifle, including the weapon jamming in extreme temperatures, led to it being suspended from the Nato nominated weapon list in 1997.

The MoD said on Tuesday that reports on the future of the rifle were "speculative" but it confirmed a report on its effectiveness would be published at the end of next week.

"We have always said that we have been testing it in stringent battlefield conditions using weapons experts in conjunction with the manufacturers so that we can compare maintenance procedures," a spokesman said.