WASHINGTON: US Secretary of State John Kerry said Wednesday that "a lot of countries" are training Syrian rebels as part of stepped up efforts to topple President Bashar al-Assad's regime.

"It's one part of it. But other nations are doing other things. There are a lot of nations working at this. And so I think President Assad needs to read the tea leaves correctly," Kerry told Fox News during a visit to Qatar.

Kerry did not say which countries were involved in the effort or whether the United States was training rebels.

"There are a lot of countries doing training," Kerry said.

"What is important is that President Assad needs to understand the re-focus of commitment in order to get him to change his current calculation, and in order to hopefully get his allies to advise him: 'You need to go to the table and negotiate a peaceful resolution.'"

The United States says it has so far refused to arm the rebels, but on Tuesday Kerry expressed confidence that weapons supplied by Gulf countries were reaching the "right people."

Washington said last month it would provide direct aid to the rebel fighters in the form of food and medical assistance, as well as $60 million in funding for the political opposition, but not the weapons they have asked for.

Kerry is due to wrap up his maiden regional tour on Wednesday after visiting Qatar, the United Arab Emirates, Saudi Arabia, Egypt and Turkey.