David Miliband urged Syria today to play a "constructive" role in the Middle East as he became the first British politician to visit the country for seven years.
After talks with President Bashar Assad in Damascus, the Foreign Secretary called on the Syrians to use their influence in the region to promote the peace process.
"Syria is a very important country with important responsibilities," Mr Miliband said.
"Syria has the opportunity to play a constructive role for peace in the region."
But he pointedly warned that Hamas rocket attacks on Israel were damaging to Syria's standing.
"I argue that Hamas's violence hurts Syria, which says it believes in a comprehensive peace," Mr Miliband said.
His visit to Syria is the first by a member of the Government since then prime minister Tony Blair in 2001.
After years of isolation, the country has more recently been applauded by western leaders for formalising diplomatic ties with neighbouring Lebanon and holding peace talks with Israel.
But it still has links to militant groups like Hezbollah in Lebanon and Hamas in Palestine.
Mr Miliband's trip to the Middle East, which has also involved talks with Israeli and Palestinian leaders, coincides with a renewal of hostilities between Israel and Hamas in the past two weeks.
He said earlier that Britain had been building relations with Damascus for about 18 months, amid "important signs" that Syria wanted to change its ways and end its international isolation.
The Foreign Secretary told the BBC: "Syria certainly has had some big questions to answer about the flow of foreign fighters into Iraq, about the situation in Lebanon, about its contribution to the stability of the region.
"We have been taking up these issues and I think there have been some important signs over the last year or so of Syria understanding the degree of concern and seeking to change some of its actions."
Israeli president Shimon Peres, visiting London today, expressed concern that Syria was "divided" - wanting both peace with Israel and continued relations with Hezbollah and Iran.
"I am afraid that Syria thinks it can make two moves - forwards and backwards - and that is a problem," he said.
"If Syria will understand that they can't have the Golan Heights and keep Lebanon as a base for the Iranians, then the decision will be clear.
"But if she wants the Golan Heights back and keeps her bases in Lebanon - which are really controlled and financed by the Iranians - no Israeli will agree to have Iranians on our borders."