Unprecedented two-week operation will see 500 tonnes of cargo travel by road and ship to Italian port by end of the year

Syria's chemical weapon arsenal is to be taken cross-country in Russian armoured trucks guarded by Syrian government troops and tracked by American satellite navigation equipment on its way to the Mediterranean coast.

The unprecedented and precarious two-week operation will take the cargo – 500 tonnes of chemical components of sarin and VX nerve agents and canisters of mustard gas – from 12 sites around the country to the port of Latakia, where they will be loaded onto Danish and Norwegian cargo ships.

China will provide surveillance cameras and ambulances on stand-by in case of any accidents, while Finland has offered to provide its own emergency response teams.

The ships will sail under Danish and Norwegian naval escort to an unnamed Italian port to be transferred to a US vessel, the Cape Ray, which will be carrying two chemical reactor chambers to neutralise the chemical weapons while at sea. On-board tankerswill store the by-products for later incineration.

The multinational plan was presented in The Hague yesterday by Ahmet Uzumcu, the director-general of the Organisation for the Prohibition of Chemical Weapons (OPCW) to the organisation's executive council, for a vote on Tuesday night.

Uzumcu warned that the ambitious timetable, by which the chemical weapons would be removed by the New Year and destroyed by the end of March, was in danger of slipping because of security concerns and bad weather. He also warned that heavy fighting around the Damascus-Homs road could also postpone the operation.

"For the transportation of chemicals from the storage sites to the port of Latakia, states parties have … provided or committed essential materials and equipment," Uzumcu said in a statement to the executive council. "Apart from supplying nearly 3,000 container drums of various capacities, the United States of America is providing GPS locators, loading, transportation, and decontamination equipment."

"The Russian Federation is providing large capacity and armoured trucks, water tanks, and other logistical supplies. It has also indicated the possibility of further monetary or material assistance, as well as security for cargo operations at the port and in Syrian territorial waters. China is providing surveillance cameras and 10 ambulances."

The Danish and Norwegian freighters will also serve in the next phase of the UN-mandated disarmament exercise, transporting less lethal precursors, used in the manufacture of chemical weapons, to commercial incinerators around the world for destruction. The whole process is due to be completed by the middle of next year.

Uzumcu said there was nearly €10m (£8.46m) in the fund established to pay for the disarmament operation, but that Japan had offered another $15m (£9.22), subject to parliamentary approval. Finland and South Korea have pledged a combined total of €750,000.

However, the total costs of the plan are likely to run to the tens of millions of pounds, and Uzumcu issued an urgent appeal for more donations.

In his address to the OPCW executive council, Uzumcu warned that the end-of-year target for removing the most lethal chemicals from Syria could be missed.

"At times, schedules have been disrupted by a combination of security concerns, clearance procedures in international transit and even inclement weather conditions," the Turkish diplomat said. The continuing heavy fighting in the Qalamoun and surrounding areas and the closure of a major arterial road between Damascus and Homs, pose risks to the timely execution of the operation. The possibility of some delays cannot be discounted."