LONDON, NOV. 30 -- The commander of Britain's armored brigade in Saudi Arabia has warned the British public to brace itself for a conflict of unprecedented intensity and heavy casualties if war breaks out in the Persian Gulf.

"It is going to be the sort of warfare people never realized, or could have expected," said Brig. Patrick Cordingley, in remarks reported today in several newspapers here. "Modern equipment and the effect it has are much more powerful than in any previous war. The results are going to be fairly terrific when they are used, and I have no doubts they will be used."

"The public is not prepared for what is about to happen out here," Cordingley told a group of British reporters at his military headquarters near Jubail, Saudi Arabia. While still hoping for a diplomatic solution, he warned: "We have got to prepare the British public for a particularly unpleasant war. They should be told there will be a lot of casualties."

The assessment by Cordingley, commander of Britain's Seventh Armored Brigade, known as the Desert Rats, was the bluntest and most pessimistic any ground commander has yet made about the possible consequences of war in the gulf. He said he based his projections in part on the likelihood that Iraqi President Saddam Hussein would use all the weapons at his disposal, including chemical and biological warheads.

His chief of staff, Maj. Ewan Loudon, told reporters that if the brigade's 9,500 combat troops were used to tackle Iraqi defensive positions in Kuwait "head-on," casualties could run as high as 15 percent.

Officials in London confirmed as accurate the accounts of Cordingley's remarks but sought to play down their importance. "It is one relatively junior officer's view," said a Defense Ministry spokesman of the brigadier, who would be a one-star general in the U.S. Army.

The spokesman also disputed Loudon's warnings of a possible 15 percent casualty rate, saying British planners have no firm estimate of the casualties they expect from an invasion of Kuwait by the U.S.-led multinational forces arrayed against Iraq.

"We have planning assumptions, but that's quite different from an estimate," said the official.

Until now, British officials have refused to offer any figure about the projected number of casualties, while American sources have said they expect rates to run as high as 8 percent per day among battle troops during an offensive. Earlier this week, the commander of Britain's gulf forces, Lt. Gen. Sir Peter de la Billiere, said he believed that any war would be brief and that casualties would not be "unnecessarily high."

But Cordingley gave a much grimmer assessment. "When two armies of this size line up against each other, it is inconceivable that casualties are not going to be large," he said. "You don't have field hospitals of the size we have got if you don't expect casualties."

British forces have established two field hospitals with a total capacity of 500 beds in the gulf, along with a hospital ship. A third field hospital is to be set up soon, officials said.

An additional 14,000 British troops are due to arrive in the gulf over the next few weeks alongside another 200,000 American troops, and Cordingley said the increase in numbers might help reduce the casualty figures.

"The larger the army the greater the chance of winning quickly, and if you have superiority, then you take fewer casualties," he said.

Reflecting the view of U.S. military planners, Cordingley said the best weather and ground conditions for an attack would be from the end of January through February.

Britain's new prime minister, John Major, made his first public remarks about the gulf crisis Thursday night, warning Iraq that Britain is ready to go to war. "The military option exists, and the international community collectively will not be afraid to use it," he told a political meeting in northwest England.