The United States plans to provide about $100 million in new non-lethal aid to the Syrian opposition that could include for the first time battlefield support equipment such as body armour and night-vision goggles, a US official said.

Secretary of State John Kerry is expected to announce the new aid package, which would mark a recalibration of US policy toward rebel groups in the Syrian civil war, at an international conference on Syria that he will attend in Turkey this weekend.

The new assistance would still stop short of supplying weapons to insurgents fighting to overthrow Syrian President Bashar al-Assad. It is also far less than what is being sought by Syrian opposition leaders, US allies like Britain and France and some US lawmakers.

But even the limited new steps under consideration suggest that the White House, amid difficult internal debate, is continuing to move slowly toward a more direct role in bolstering the Syrian opposition.

Providing body armour and night-vision goggles "would be consistent with the president's directive to look for ways to increase assistance to the opposition," the US official said.

Kerry is expected to formally unveil the US decision at a meeting in Istanbul on Saturday with Syrian opposition leaders and their international backers. Fresh US humanitarian aide for Syrian refugees is also likely.

A senior State Department official said "assistance to the Supreme Military Council (of the rebel Free Syrian Army), beyond military food rations and medical kits to include other types of non-lethal supplies, is... being discussed, and will be determined in collaboration with SMC leadership."

US officials have said in the past that the equipment could include armoured vehicles and advanced communications equipment.

The 11-nation "core group" of the Friends of Syria, including the United States, European and Arab nations, has been deadlocked over how to remove Assad, whose security forces killed and arrested thousands of protesters who took to the streets to demand democratic reforms in March 2011.

More than 70,000 have been killed in the revolt and subsequent civil war. But a military stalemate has set in and much of Syria is left in ruins because of a divided and ineffective opposition, a lack of action by foreign allies and Assad's ability to rely on support from Russia and Iran.

PACKAGE STILL BEING FINALIZED

The latest US expansion of non-lethal aid will follow Kerry's announcement in Rome in late February that Washington would shift policy to provide medical supplies and food directly to opposition fighters, an option it had previously rejected.

The exact amount and composition of the aid package was still being finalised, and it was not yet decided whether the new military equipment would go directly to certain rebel groups or be channeled through the civilian opposition, the official said.

The United States so far has provided $117 million in non-lethal assistance, the White House said. That has included communications gear and governance training for the civilian opposition.

Despite pressure from some members of Congress and recommendations even from among his own advisers, Obama has refused to supply arms to the rebels, reflecting concern that such weapons would fall into the hands of Islamist militants in the ranks of the fractious insurgency.

Saudi Arabia and Qatar are among Arab states believed to be arming rebel factions.

"We continue to weigh the risk that any weapons we might contribute that would make a real difference could wind up in the hands of extremists - and come back to hurt us and our partners in the region," White House spokeswoman Caitlin Hayden said. "Other countries are making their own decisions about lethal assistance." – Reuters