* Hague says new coalition needs support within Syria
* Says not excluding any option to support opposition
CAIRO, Nov 13 (Reuters) - British Foreign Secretary William Hague welcomed the latest effort by Syria's opposition to form a united front against Bashar al-Assad, but said more needed to be done before Britain formally recognised it.
Exiled opposition leaders formed a coalition on Sunday and the grouping is now seeking international recognition as a government-in-waiting.
Western powers demanding that Syrian leader Assad step down to end a 19-month rebellion have been frustrated by squabbling among his opponents.
"It is a very important milestone," Hague told reporters at a meeting of Arab and European ministers at the Arab League in Cairo on Tuesday.
"We want the Syrian opposition to be inclusive ... and to have support inside Syria and if they have this, yes, we will then recognise them as the legitimate representative of the Syrian people."
He said that did not imply that Britain would be ready to send weapons to the opposition because the European Union had placed an arms embargo on Syria.
But he added: "But we are not excluding any option in the future because ... the Syrian crisis is getting worse and worse all the time".
Some 2.5 million people have been internally displaced by the country's civil war, double the previous figure of 1.2 million used by aid agencies, the United Nations refugee agency said, citing the Syrian Arab Red Crescent.
Hague said more needed to be done by the European Union and the Arab League to press for global assistance for Syrian civil society and human rights groups, according to a statement issued by Britain's Foreign Office on Tuesday.
"The winter cold and rain will heap further misery on soaring numbers of Syrian refugees and displaced people," he said in the statement.