Nations including Syria, Iraq and Israel should join a landmark pact for destroying stockpiles of chemical weapons as they serve hardly any security or strategic purpose, a watchdog agency said on Friday.

Rogelio Pfirter, director-general at the Hague-based Organisation for the Prohibition of Chemical Weapons (OPCW), made the appeal ahead of a review conference next week.

So far 183 countries have ratified the 1997 Chemical Weapons Convention banning the use, development, production, stockpiling and transfer of chemical weapons but the OPCW wants more states to join up.

"Chemical weapons basically terrorise civilians, they are of relatively little security or strategic use these days," Pfirter told Reuters in an interview.

"It is hard to see how these weapons can make any contribution to peace," he said.

Israel, Myanmar, Bahamas, Dominican Republic and Guinea-Bissau have signed up to the treaty but have not ratified it, the watchdog said. Iraq, Syria, Egypt, North Korea, Somalia, Lebanon and Angola have shunned it.

Regional conflict and internal problems are among the major obstacles to these countries becoming members to the convention, said Pfirter.

"We hope these countries, irrespective of the fact they have a crisis there, will realise they should join," he said.

He said officials from some of those countries will attend next week's review conference.

"We take it as a very good sign of continued interest in the convention."

Since it signed up to the treaty, Russia has destroyed nearly a quarter of its stockpile and the United States close to 50 percent. The two countries have an extended 2012 deadline to destroy the rest of their stockpiles.

Asked if the two countries can meet their deadline, Pfirter said: "At this stage, it would be very premature to speculate one way or other. One should continue to expect they will do anything possible to continue destruction of their stockpiles."

Libya, a signatory to the pact since 2004 after it started emerging from international isolation by agreeing to halt its weapons programmes, is expected to destroy its entire stockpile by 2011.