Inspectors who will oversee the destruction of Syria's chemical weapons said on Sunday that their first priority was to end the country's manufacturing capability by November 1.

The Organisation for the Prohibition of Chemical Weapons (OPCW) said that may include smashing mixing equipment with sledgehammers, blowing up delivery missiles, driving tanks over empty shells or filling them with concrete and running machines without lubricant so they seize up and become inoperable.

On Sunday, OPCW inspectors met reporters in The Hague to explain their plan of action.

"This isn't just extraordinary for the OPCW," said spokesman Michael Luhan.

"It hasn't been done before - a mission to go into a country which is involved in conflict and oversee the destruction of an entire category of weapons of mass destruction.

"This is definitely an historical first."

The chemical weapons are distributed over around 60 sites.

An initial group of 20 investigators flew out today and will meet their Syrian counterparts tomorrow to begin planning.

Protection will be provided by the Syrian government with support from the UN, which has open lines of communication with rebel groups.

But access to weapons sites in rebel-held territory would be dealt with on a case-by-case basis, with the UN possibly helping to negotiate safe passage.

"It may be that we are not in a position to go to some places," Mr Luhan said.

"This is not a mission that will be carried out come what may."