LONDON — While the world’s diplomats work in New York to hammer out an agreement on the disposal of Syria’s chemical weapons, and United Nations investigators head back into Syria, experts say fighting in the more than two-year-long civil war may well become more intense.

Syria could be losing all or most of its chemical weapons, which gave it a significant advantage over rebel forces. Experts say that could lead to intensified attacks from both sides.

Retired British Brigadier Ben Barry, now at the International Institute for Strategic Studies, says with the loss of its chemical weapons, the Syrian government is likely to make more extensive use of its other military assets.

“That has reduced an element of the regime’s military advantage. But of course the regime still has lots of heavy firepower, including tanks, mortars, artillery and ground-launched rockets, which is a much more important part of its capability,” Barry explained.

According to experts at the Institute, last month’s chemical weapons attack and the lack of a Western military response has left the rebels feeling disappointed and abandoned. They say that will likely move the rebels to take a more aggressive approach on the battlefield. Emile Hokayem, a senior fellow at the institute’s Middle East Center, predicts a significant spike in violence.

“Actually, I think that in coming months, in fact, the fighting is going to increase massively, and we will probably see even more massacres, just because there is a sense right now that there is no outside help coming, so it’s a free-for-all,” Hokayem said.

And that would make it more difficult for United Nations inspectors to find and destroy or transport Syria’s chemical weapons. Still, if Russia restrains Syrian government forces and the West convinces the rebels not to interfere with the inspectors, U.N. Secretary-General Ban Ki-moon thinks the plan could work.

“Both sides who have influence on government forces and opposition forces could influence political pressure or whatever. I think that can be done. Yes,” admitted Ban.

That will be tested this week, as a team of inspectors arrives in Syria. And experts are not convinced that cooperation will be a priority for neither the government nor the rebels.