AMMAN (Reuters) -- Syrian rebels on Sunday seized a Syrian military intelligence compound in the southern Hauran Plain near the Israeli-occupied Golan Heights, rebel commanders said.

The frontier, quiet since Israel and Syria agreed on a US-brokered ceasefire in 1974, has turned volatile in recent weeks, after opposition brigades stepped up attacks against army and intelligence compounds dotting the agricultural plain stretching from the border with Jordan to the Damascus outskirts.

The compound near the Yarmouk River in the town of Shagara, 8 km from a ceasefire line with Israel, fell after a five-day siege, the sources said.

"We have completely taken over this security compound this morning. It's a command centre for the shabbiha (pro-Assad militia). They retreated after strong blows dealt to them during a five day siege," said Abu Iyas al-Haurani, a member of the Yarmouk Martyrs Brigade.

"Anyone who was arrested in the Yarmouk Valley was sent to this military intelligence headquarters to be tortured and it has a strategic importance. With its fall we have completed our liberation of the town of Shagara," he added.

Another rebel commander said the aim of the attacks in Western Hauran is to open a new front in the fight against President Bashar Assad that would stretch troops deployed in Hauran, cradle of the two-year revolt, and to secure a supply route to the western approaches of Damascus.