The fresh move, involving the departments of state, commerce and Treasury, aimed to enable additional relief and reconstruction activities in militants-controlled areas of Syria, the State Department said in a statement.

A limited waiver signed by Secretary of State John Kerry authorizes the export and re-export of certain US-origin items to militant-controlled areas in Syria, including commodities, software and technology, among them water supply and sanitation, agricultural production and food processing, power generation, oil and gas production, construction and engineering, transportation and educational infrastructure.

"Of note, the export of food and medicine does not currently require a license and medical devices are covered under an existing waiver," the statement said.

The Treasury, for its part, issued a Statement of Licensing Policy (SLP) inviting American citizens to apply for specific licenses that enable them to participate in certain economic activities in Syria.

"The SLP specifically focuses on applications by US persons seeking to engage in oil-related transactions,” said the statement.

The Syrian foreign-backed rebels were losing ground in their 26-month conflict with the government, as they lost the border city of al-Qussair early this month.

The Syrian army has launched a fresh opperation to secure the countryside of northern province of Aleppo.

As the Obama administration was discussing arming the Syrian terrorist groups, Kerry and his British counterpart William Hague vowed on Wednesday to do their utmost to provide required military equipments.

"We are determined to do everything that we can," Kerry told reporters following his talks with Hague at the State Department.

"The United Kingdom believes that the situation demands a strong, coordinated and determined approach by the UK, the U.S. and our allies in Europe and the region," Hague said.

The European Union lifted its arms embargo on the Syrian militant groups in late May.