Iraq has fired up to five Scud missiles at Kuwait, US and Kuwaiti officials have said, prompting troops to don chemical protective suits and setting emergency air raid sirens blaring in Kuwait City.
Iraq, however, has denied the claim saying the country does not possess any Scuds.
Later a "steady barrage" of artillery fire, apparently from US troops, was heard on the border between Kuwait and Iraq at about 11.45 a.m., reports said.
A Kuwaiti defence ministry spokesman said one Iraqi Scud hit northern Kuwait at about 9.40 a.m., while US officers said two Scuds hit Kuwait, and another two were inbound.
In a slightly conflicting report, a British military spokesman said Iraq had fired just one Scud, which was brought down by a US Patriot missile defence battery.
"One (Scud) was knocked by a Patriot system. Where the debris landed I'm not sure. The debris is being investigated at this moment. What we can say is there are no casualties," said the spokesman at a US-British military headquarters in Qatar.
The Iraq information minister denied that Baghdad had any Scuds. The Soviet-designed missiles have a range of up to 650 km, exceeding the 150-km maximum limit imposed on Iraq after the 1991 Gulf war.
Earlier today Iraq fired two other missiles into the northern desert, but Kuwaiti officials described these weapons as smaller, Chinese-made missiles. The British spokesman said Iraq had fired two seersucker anti-ship missiles.
US military arrayed in northern Kuwait for an invasion of Iraq were given a "bunker call" to shelter from possible unconventional attack, reporters attached to the units said.
Soldiers were told there was an incoming Scud missile and were ordered to move to the highest level of biochemical protection, donning their protective suits, gas masks, gloves and boots and taking up an attack position.
Ten minutes later they were given the all-clear. Officers said it was not clear whether the alert was a drill or whether it had been prompted by an incoming Scud.
In Kuwait City, emergency air raid sirens blared, an all-clear was heard, and then fresh sirens were sounded.
A security official said that the city had not been hit by any Iraqi attack but added that unspecified blasts in the desert had echoed through the streets and unsettled residents.
The Iraqi missile attacks marked one of Baghdad's first retaliations after the United States bombed Baghdad early today, launching a war that US President George W. Bush has vowed will topple President Saddam Hussein.