The United States has stepped up its support for the Syrian opposition with additional 60 million U.S. dollars in non-lethal assistance, U.S. Secretary of State John Kerry said here on Thursday after an international meeting on Syria.

The U.S. would provide such aids as food and medical supplies for the first time to rebels battling against the regime of Syrian President Bashar al-Assad, Kerry announced in a joint press conference in Rome with Italian foreign minister Giulio Terzi and Syrian opposition leader Mouaz al-Khatib.

"Assad is out of time and must be out of power," Kerry said, adding that all ministers in the meeting had agreed to increase the pressure on Assad to step down.

According to a statement from Italy's foreign ministry, ministers from the U.S., Arab and European countries pledged more political and material support to the Syrian opposition while underlining the need to "change the balance of power on the ground."

Washington has provided 385 million dollars in humanitarian aid to Syrian people and 54 million dollars in medical supplies, communications equipment and other nonlethal assistance. But it has been the first time that the U.S. decides to offer aids directly to rebels.

"The U.S. believes that the Syrian opposition can lead the way to a peaceful transition, but cannot do it alone.. All Syrian people must know that they can have a future in a post-Assad era, " Kerry said.

The U.S. decision to take further steps was the result of increased brutality of Assad, Kerry said, recalling the deadly explosions in Syria's capital Damascus last week.

The Syrian opposition was in fact persuaded by Kerry to attend the meeting, before which it had threatened to boycott the conference as a protest against little help from the West.

"Today's meeting is only part of a whole, and I am confident that the whole will be able to make Assad realize what choices he has," Kerry added, referring to further moves with its allies to speed up peaceful transition in Syria.

At the end of the joint press conference, an Italian woman in the seats for press abruptly shouted that the U.S. was preparing for war and that "it's a shame." The protestor later told Xinhua that she acted as a peace activist although she was working for local newspapers.

The meeting on Syria was widely considered as the centerpiece of Kerry's first overseas mission since taking office. He arrived in Rome on Wednesday in the middle of an 11-day tour of Europe and the Middle East.