BRUSSELS (AFP) - Iran could show it wants to play a constructive role in upcoming Syrian peace talks by urging the Damascus regime to halt bombardments of civilians and allow aid access, US officials said on Monday.

"There are also steps that Iran could take to show the international community that they are serious about being a positive player," a senior State Department official told reporters travelling with Secretary of State John Kerry.

"Those include calling for an end to the bombardment by the Syrian regime of their own people, it includes calling for encouraging humanitarian access."