Prime Minister David Cameron has set timetable of 2015 for troop withdrawal, but the Nationalists want more immediate action and say there should greater focus on humanitarian efforts to rebuild communities across the region.
Britain has 10,000 of the 130,000 Nato troops in Afghanistan and more than 100 UK troops were killed in 2010. This year will mark the decade anniversary of the invasion of the country in 2001 to overthrow the Taleban regime.
US president Barack Obama has already said that the 65,000 US troops will end combat operations this year, although many will remain in the country to advise Iraqi forces and protect US interests.
SNP Westminster leader Angus Robertson said: "President Obama has already stated his intention to bring American troops home by July 2011.
"If the US president can offer such certainty, why are British service personnel being fobbed off with vague commitments?
"UK involvement in Afghanistan has now lasted longer that either of the world wars. If David Cameron is to make a New Year's resolution, it should be to bring troops home by Christmas 2011.
"Now is the time to focus on humanitarian efforts to ensure long-term stability in the region.
"As the UK's former ambassador to the UN Sir Jeremy Greenstock says, the army has been 'holding a wall up' in Helmand, but 'no-one has come along to build a buttress' of development."
A total of 348 UK service personnel have been killed in operations in Afghanistan since 2001. It is proving almost twice as dangerous as Iraq, where there have been 179 deaths, including 136 in action.
The latest death came four days ago, when Warrant Officer Charlie Wood of the Royal Logistic Corps, 23 Pioneer Regiment died in an explosion as he was clearing roadside devices.
Mr Cameron told the Nato summit in Lisbon that Afghan forces would gradually take charge of security and have total control by 2014. That would let British forces step back from combat roles by a "firm deadline" of 2015, although some would stay to train Afghan forces.
Nato has itself set a timeline up to 2014, by which time transition will be complete. Afghan president Hamid Karzai and Nato secretary-general Anders Rasmussen recently signed a deal for the "irreversible transition" to Afghan control by the end of 2014.
But critics have also pointed to the massive bill for military operations in Afghanistan in the current economic climate; the cost topped 2.6 billion between 2008 and 2009 - about 7.2million a day.
The SNP has been joined in its appeal for early withdrawal by Welsh Nationalists Plaid Cymru.
"The Prime Minister has made repeated hints and has even admitted that withdrawal from Afghanistan is ‘eminently do-able' - but we need much firmer commitment now," said Plaid Westminster leader Elfyn Llwyd.
"We need a phased exit strategy to begin immediately and for the full transfer of security to Afghan control."
He added: "Military and civilian deaths were at an all time high last year and I dearly hope that we do not lose another man or woman in 2011."