Washington  - Democratic presidential candidate Barack Obama spoke out against ongoing rumours questioning his religious beliefs and heritage in a broad speech on patriotism Monday ahead of US Independence Day celebrations.

Speaking from the aptly named town of Independence, Missouri, Obama directly addressed the series of false rumours that have plagued his campaign, including that he is of the Muslim faith and refuses to pledge allegiance to the US flag - a daily practise in most schools across the United States.

"At certain times over the last 16 months, I have found, for the first time, my patriotism challenged - at times as a result of my own carelessness, but more often as a result of a desire by some to score political points and raise fears about who I am and what I stand for," Obama said.

"I will never question the patriotism of others in this campaign, and I will not stand idly by when I hear others question mine," he said.

Obama's campaign last month set up a website (www. fightthesmears. com) to counter rumours that have spread mostly through email and the internet.

Polls have shown that about 10 per cent of Americans believe Obama is Muslim. The Illinois senator is in fact Christian, though he was only baptized as an adult.

Obama also criticized the use of patriotism as a "political sword or political shield" to attack opponents of government policy - never mentioning the Bush administration by name but speaking broadly of the current political climate.

"Patriotism can never be defined as loyalty to any particular leader or government or policy," Obama said. "When our laws, our leaders or our government are out of alignment with our ideals, then the dissent of ordinary Americans may prove to be one of the truest." (dpa)