LONDON: U.S. Secretary of State John Kerry tried Monday to patch back together a conference with Syrian opposition leaders that was to be the centerpiece of his debut overseas trip, urging Syrian rebel leaders not to boycott the meeting and insisting that more help is on the way in their fight against President Bashar Assad.

Kerry not only made a public plea at a joint news conference Monday with British Foreign Secretary William Hague, he also called Moaz Khatib, leader of the Syrian Opposition Council, "to encourage him to come to Rome," a senior U.S. official said. The official spoke on condition of anonymity because he wasn't authorized to speak publicly on the matter.

Kerry was in London for the first leg of his first trip as secretary of state - a hectic nine-country dash through Europe and the Middle East. The trip includes a Syrian opposition conference Thursday in Rome, which some members of the sharply divided Syrian opposition council have threatened to boycott.

Kerry also dispatched his top Syrian envoy to Cairo in hopes of convincing opposition leaders that their participation in the conference in Rome is critical to addressing questions from potential donors and securing additional aid from the United States and Europe.

The Rome meeting is the centerpiece of Kerry's nine-nation tour of Europe and the Middle East

"We are not coming to Rome simply to talk," Kerry told reporters in London. "We are coming to Rome to talk about next steps."

Kerry said he was sympathetic to the opposition's complaints that the international community had not done enough, and noted that as a senator he had called for the Obama administration to consider military aid to the Syrian opposition.

But he also noted that he now is part of the administration and "and the president of the United States has sent me here ... because he is concerned about the course of events."

"This moment is ripe for us to be considering what more we can do," he said, adding that if the opposition wants results, "join us."

Meanwhile, Syrian Foreign Minister Walid al-Moallem said Monday the regime of President Bashar Assad was ready to hold talks with opposition leaders, the first time that a high-ranking Syrian official has stated publicly that the government would meet with the opposition. Al-Moallem made his comments after meeting in Moscow with Russian officials.

Administration officials have debated whether the U.S. should arm the rebels, with Defense Secretary Leon Panetta and Joint Chiefs of Staff Chairman Gen. Martin Dempsey having said they urged such a course of action.

The White House has been unwilling to do so for fears the weapons could end up in the wrong hands. Currently, the U.S. provides only non-lethal support and humanitarian aid.

The United Nations says at least 70,000 people have been killed in Syria's 2-year civil war, which began as an uprising against Assad's regime.

"We are determined that the Syrian opposition is not going to be dangling in the wind, wondering where the support is, if it is coming," he said. ""We are not going to let the Syrian opposition not have its ability to have its voice properly heard in this process."

Kerry said the Syrian people "deserve better" than the violence currently gripping their country as he stood alongside Britain's Foreign Secretary William Hague.

Hague also stressed the need for action, saying an "appalling injustice" is being done to Syrian citizens.

"In the face of such murder and threat of instability, our policy cannot stay static as the weeks go by," Hague told the press conference. "We must significantly increase support for the Syrian opposition. We are preparing to do just that."

Associated Press writer Cassandra Vinograd contributed to this report.