As US President Barack Obama readies to send extra troops to Afghanistan, NATO cautioned Wednesday that a number of US allies could wait until next year before following suit with reinforcements.

Obama is set to announce on December 1 the deployment of tens of thousands of extra troops to "finish the job" of beating a tough Taliban-led insurgency, eight years after US-led forces ousted the fundamentalist militia from power.

- Nobody should expect that the day after President Obama makes his announcement that there will be a total troop figure, added up and put on the table, from the other allies - said NATO spokesman James Appathurai.

Obama is set to change strategy in Afghanistan, with forces protecting civilians to win their trust and isolate the insurgents, rather than hunting down the militants who now hold the initiative.

Appathurai said a small group of NATO heavyweights, led by Germany, want to wait until after a new international conference on Afghanistan, tentatively set for January either in London or Kabul, before committing more resources.

- They want to see any further any contributions in context of the overall political environment in which they will be deploying their forces. That is a thoroughly understandable position - he said.

- There are real questions in our publics about the way forward, politically and not just militarily - he said. A rise in civilian and troop casualties has undermined public support for NATO's mission, both in Afghanistan and at home.

NATO Secretary General Anders Fogh Rasmussen was due in Rome Wednesday for talks on troops with Italian Prime Minister Silvio Berlusconi, and will travel to Berlin Thursday for a similar meeting with Chancellor Angela Merkel.

- It is important for the political balance in this mission that there is a commensurate contribution also from the other allies - once Washington makes its intentions known, Appathurai said.

Britain has said NATO's 28 nations plus more than a dozen partners with them in Afghanistan could stump up a further 5,000 troops on top of the US surge.

London has said it would send an extra 500 soldiers if Kabul commits to provide police and soldiers who can be trained to engage in combat; if British troops are well equipped and if other NATO countries boost force levels.

But France's President Nicolas Sarkozy said already in October that France would not send a single soldier more. He said France would stay in Afghanistan but he was "convinced" more Afghan soldiers were needed to defeat the Taliban insurgency.