The commander of British forces in the 1991 Gulf war yesterday revealed he had suffered flu after receiving injections before the conflict.

General Sir Peter de la Billière told Lord Lloyd's inquiry into possible war-related illnesses he had been "positively unwell", the latest veteran to report reactions to jabs soon after they had them.

A combination of injections, including against smallpox, anthrax and plague, and tablets to protect against nerve agents, has been blamed by some for illness soon after they received them as well as for long-term conditions.

But Sir Peter, whose illness was shortlived, said it had been essential to protect troops against the chemical and biological weapons that Saddam Hussein was known to have.

The injections were "voluntary, as far as I am aware, although I don't think people were encouraged not to accept them". It would be an unwise commander who did not seek to take every precaution to protect his troops, he said.

"That would certainly be the way I would see it and the way I would have wished it to be, too. I was responsible for the lives of these people. I had to take it for granted that what was made available to me was safe and worth using."

Sir Peter posited stress of battle and organophosphate flysprays used to protect troops from disease as other possible causes.

Allied commanders believed attempts to go through the minefields protecting occupied Kuwait and Iraq might result in high casualties. These would be 5% higher if Saddam used chemical or biological weapons, "a relatively small" extra percentage because of protection provided for troops.

He received "somewhere around nine" injections. "I was positively unwell for about 48 hours. I would describe it as a dose of unwelcome flu. One kept going because you don't give into a spot of flu when you are on operations. It certainly affected my performance. I think many other people suffered much the same."

He could not remember which injection had been responsible "but we were warned one of them might affect some more than others".

Sir Peter added: "As far as my memory serves me, some of the injections were relatively new and had not been used so widely in terms of numbers of people and, arguably, for such a long time, and possibly not in the atmospheric conditions of the Middle East, although it was not exceedingly hot."

Although stress was a part of any war, he said his troops "had this extraordinary situation of a massive period of waiting and anticipating the type of warfare that none of them had been involved in before, using equipment that had been tested in trials and training but never in warfare".

Possible poisoning through flysprays should also be investigated, he said. They had been bought locally and had Arabic instructions. He believed troops in tanks and in the desert might have been exposed to more spray than commanders in Riyadh. Some might not have had sufficient water to wash it off.

Sir Peter joined two former heads of the defence staff, Lord Craig and Lord Bramall, in urging the government to settle the conflict with veterans over the causes of their illness. "If you delay it much longer a lot of people are going to be dead who should have benefited, but never will."

The government has refused a public inquiry into the issue but research is continuing. Serving ministers, civil servants and military staff will not attend the Lloyd inquiry, which is funded by donations.