* Plastic explosive found in pickup's exhaust pipe

* Country foiled al Qaeda attack in 2009

KUWAIT - Kuwaiti police dogs sniffed out plastic explosives hidden in a pickup truck that was trying to enter an industrial seaport in the Gulf Arab state, security officials said on Monday.

They said the driver of the truck, which belonged to the Electricity and Water Ministry, was taken into custody. They described him as an Asian national but gave no further details.

"The suspected explosive material was found in a white pickup's exhaust, entering Shuaiba port on Saturday," one of the officials said, speaking on condition of anonymity. "The substance is C4 and is the size of two fingers."

C4 is a high-velocity military explosive.

Another security official said there was no immediate indication the explosive was to be used in a militant attack in the world's fourth-largest oil exporting country but investigations were still in progress.

Authorities carried out a security sweep at Shuaiba port, home to one of the country's three crude oil refineries, after the truck was stopped, one of the officials said. The port is in the south of Kuwait city.

In 2009, Kuwait foiled an al Qaeda-linked plan to bomb a US Army camp and other facilities in the country, including the state security building.

Kuwait, the launch pad for the 2003 US-led war on Iraq which ousted Iraqi leader Saddam Hussein, remains a logistics base for the US Army to support its troops in Iraq.