By Rob Watson BBC correspondent in Washington

A man claiming to have explosives has brought much of downtown Washington to a standstill for a second day, in a bizarre protest against the government.

Dwight Watson drove his tractor through the centre of the capital

Even with the US on the brink of war with Iraq, the talk in this town is of just this man - Dwight Watson.

It all started at around noon local time (1700 GMT) on Monday when Mr Watson drove his tractor into a pond in Washington's famous mall, home to its treasured monuments.

Mr Watson is a 50-year-old tobacco farmer from North Carolina and an unhappy one at that.

He is protesting against the government's cuts in subsidies to tobacco farmers, which he says is making it impossible to run his farm.

Total chaos

Mr Watson is said to have told the police that he is packing explosives and that explains why he is now surrounded by 100 officers, some with sniper scopes aimed in his direction.

Security forces have surrounded the tractor for hours

The result of the standoff is total chaos, with cars and pedestrians forbidden to enter the normally busy area.

With the city already jittery in the face of a heightened terrorist alert, this has hardly helped the mood, but it has not stopped the jokes.