Gaza, Aug 15 (IANS) A senior Palestinian official warned that the closure of the sole Israeli-controlled commercial crossing point of Kerem Shalon is threatening 400 factories in the Gaza Strip.

Sami al-Amassi, president of the General Federation of the Palestinian Trade Union, said in a statement on Friday that his union warns of the repercussions of the closure, reports Xinhua news agency.

On August 11, Israel closed the crossing after militants in the besieged Palestinian enclave launched incendiary balloons into Israeli territory.

He said that the closure and banning of shipment of construction materials and fuels, has paralysed construction industries and public transport sectors.

He noted the development would indirectly cause harm to more than 40,000 workers who work in construction and metal industries.

In response to launching dozens of arson balloons, which carry explosives, Israel tightened the blockade it has been imposing on the Gaza Strip since 2007.

The Israeli authorities also cut fishing range off the Gaza Strip coast from 15 nautical miles to 8 miles.

Israeli warplanes and artilleries carried out attacks on militants' facilities and posts.

"This is a collective punishment because the commercial crossing point is the main artery for life in the Gaza Strip, mainly the labour sector," al-Amassi said, adding that around 150,000 workers are part of this sector.