MADRID — Prime Minister Jose Luis Rodriguez Zapatero said Wednesday that Spain was willing to increase its troops on long-term assignment in Afghanistan, in what appeared to be a gesture of support to the Obama administration.

Spain’s Socialist government has long resisted calls from the United States and other NATO allies to increase its Afghan force.

Zapatero said the move could be achieved by prolonging a temporary deployment of forces who had been sent to help with security in Afghanistan ahead of the Aug. 20 presidential election.

“We’ve always been willing to provide additional troops in order to support elections, as we are doing currently,” Zapatero said in an interview in his office in the Moncloa Palace here. “And if there is the need to sustain a greater number of presences in Afghanistan, we are willing to do so.”

Spain has about 800 troops in Afghanistan, mostly in Herat and Badghis provinces, in the country’s northwest. It recently sent an additional contingent of 450 soldiers to provide extra security before the election.

“I think they are working in an area where their contribution is positively acknowledged, and we will be willing to sustain our efforts in the future if so required,” said Zapatero, who is to assume the rotating presidency of the European Union in January.

Still, Spain’s troop levels are about a third the size of France’s or Germany’s, in a combined NATO force of 64,000. Zapatero was one of Europe’s harshest critics of the Bush administration, and especially of the war in Iraq, although Spain has maintained a presence in Afghanistan since 2002.

The move toward an increased troop presence seemed intended to address the Obama administration’s request for help in Afghanistan.

President Barack Obama has been working to shift the American military focus from Iraq to Afghanistan, where the United States has been fighting the Taliban and al-Qaida militants for nearly eight years.

“Things have changed an awful lot,” Zapatero said. “I think Obama is a person who listens. I think he’s humble enough to understand, and humble enough to understand the diversity and complexity of the world, in terms of cultures, terms of ways of living, in terms of religions, in terms of different perspectives on a world order.”

“It’s not so much a question of what can Obama can do for us, but what we can do for Obama,” Zapatero said.