LONDON - Public support for the war in Afghanistan is falling, while more than 40 percent do not understand why British troops are fighting there, a poll released on Remembrance Sunday showed.

Some 64 percent agreed that "the war in Afghanistan is unwinnable", up six percent from July, while 27 percent disagreed, down four percent. Ten percent said they did not know.

Similar numbers said British forces should be withdrawn as quickly as possible, with 63 percent agreeing and 31 percent disagreeing.

Some 54 percent felt they had "a good understanding of the purpose of Britain's mission in Afghanistan", with 42 percent disagreeing.

"Overall there is the sense that Afghanistan is becoming for (British Prime Minister) Gordon Brown what Iraq became for (his predecessor) Tony Blair," said Andrew Hawkins, chief executive of pollsters ComRes.

"More than four in 10 don't understand Britain's mission; support for the British presence there is ebbing away, and a majority have responded to the presidential election very negatively indeed.

"The results suggest that the impact of the war must be having an impact on Labour support, since it is that party's core supporters who are most strongly opposed to it."

Meanwhile 52 percent agreed that "the levels of corruption involved in the recent presidential election show the war in Afghanistan is not worth fighting for." Thirty-six percent disagreed.

"This is potentially devastating for the government's case for war," said Hawkins.

ComRes surveyed 1,009 adults of different ages and social classes across Britain for BBC television's "The Politics Show".