"We recommend that all Americans in Kuwait should keep a low
profile and to be alert to their surrounding all the time," said a warden message on Tuesday, addressed to more than 8000 US citizens in Kuwait.

The message said that there were "at least three separate incidents on December 14," during which "shots were fired at US military personnel in Kuwait, lightly injuring several of them." 

"While the Kuwaiti authorities and US military investigated the
attacks, the embassy recommends that Americans avoid unnecessary travel to military installations frequented by US forces," it added.

The British embassy in Kuwait has not changed its advice issued last month warning nationals "that there is a significant threat from terrorism." 

Prime suspect held

The US military spokesman in Kuwait, Lieutenant Colonel Vic Harris, said at least four US soldiers received minor wounds from broken glass when shots were fired at military convoys in two separate incidents on Sunday.

A third shooting later that night caused no injuries, according to the US embassy message. 

A senior security source, meanwhile, confirmed on Tuesday that the prime suspect, a Kuwaiti national, was arrested on Monday evening along with three other Kuwaiti suspects.

The arrest was made at the suspect's home in Rigga, 30km south of the capital, and came after an attack on a bus carrying Asians and Egyptians working for a factory in the oil and industrial area of Shuaiba, wounding at least five of them. 

Local newspapers reported that the assailants shot at the bus because they believed it was carrying US troops. 

GCC summit

US troops operate almost exclusively in the area's port, which is Kuwait's second commercial terminal, to unload arms, weapons and equipment for the US army in Kuwait and Iraq. 

The string of attacks came ahead of a 21-22 December summit of the Gulf Cooperation Council (GCC) in Kuwait, during which cooperation in combating terrorism is expected to top the agenda.

Kuwait stepped up security after intercepting on Friday three letter bombs sent to journalists, and a small explosion at a newspaper the previous day. 

Security measures had already been heightened in preparation for the GCC summit and the Gulf Cup soccer tournament from 24 December to 11 January.