By Brian Rowan BBC Northern Ireland security editor

Sources believe the government could declare its new position soon

The government hopes to have an alternative for plastic bullets before the end of this year and the riot control weapon could be withdrawn by then, the BBC has learned.

The issue is part of the continuing discussions between Sinn Fein and the UK government.

No one is suggesting that an end to plastic bullets is guaranteed by the end of this year.

But what appears to be on offer is a speeding up of the research programme and a commitment from the government that if an acceptable, effective and less lethal alternative is available, then plastic bullets would no longer be used after the end of this year.

Two possible alternatives are currently being considered, but it had been thought the research programme would run well into next year.

'Clear timetable'

Sources believe the government could declare its new position soon - possibly even before next week when the British and Irish prime ministers are due back at Hillsborough to publish their "acts of completion" document.

The use of plastic bullets is one of a number of key issues that Sinn Fein has highlighted in its continuing talks with the government.

That's not something most law-abiding people would want to see Gregory Campbell DUP

The others are an improved Catholic representation within the police service and moves to restrict the future role of the PSNI Special Branch.

Progress is also being reported on these issues - but not on the critical matter of precisely when policing and justice powers will be transferred to local politicians.

A clear timetable for this is seen as key to Sinn Fein endorsing the new policing arrangements.

Sinn Fein's Mitchel McLaughlin said it had been one of the key issues it had been addressing in discussions with the British Government.

"We want to see a ban on this lethal weapon," he said.

"We want this immediately - it is obviously a political issue for our community."

However, Gregory Campbell of the Democratic Unionist Party said the safety of the security forces could not be compromised.

"If Sinn Fein or anyone else are going to argue for a low-key weapon that is really ineffective in the face of a mob, that's not something most law-abiding people would want to see," he said.

"They would want to see an effective weapon with strict controls over its use in order that innocent people - both security services and civilians alike - can be protected from mobs throwing petrol bombs and stones."