The humanitarian situation in Syria is worsening, says U.N aid chief Valerie Amos, with an estimated 2.5 million Syrians in need of help.

Amos said the number of those in crisis has more than doubled in the past five months.

(SOUNDBITE) (English) UN HUMANITARIAN RELIEF COORDINATOR, VALERIE AMOS, SAYING:

"The humanitarian situation has worsened since I was here in March. Over a million people have been uprooted and face destitution. Perhaps a million more have urgent humanitarian needs due to the widening impact of the crisis on the economy and on people's livelihoods."

Some fear the conflict is spilling across the region, after a mass kidnapping of Syrian refugees in Lebanon on Wednesday.

Seen here, Lebanese Shi'ite gunmen kidnapped more than 20 people in retaliation for the capture of one of their kinsmen in Syria, prompting Sunni Gulf states to warn their citizens to leave Lebanon immediately.

But Mahmod, one Syrian refugee in Turkey, says he thinks the Syrian government is behind the kidnappings, as their hold on power at home loosens.

The Syrian conflict has escalated sectarian tensions in Lebanon, with its Sunnis mainly supporting Syria's rebels, while Shi'ites, including the powerful militant group Hezbollah, mainly backing president Bashar al-Assad.