Washington  - Democratic presidential candidate Barack Obama called on Americans to engage in more community service on Wednesday as the United States prepared to celebrate its independence, and sharply criticized the current administration for relying on military options.

President George W Bush had failed to take advantage of an outpouring of support after the September 11, 2001, terrorist attacks and had placed far too great a strain on US military forces through wars in Iraq and Afghanistan, Obama said.

"The burden of service has fallen almost exclusively onto the backs of our military," Obama said at a rally in Colorado Springs, Colorado. "We have got to have a civilian national security force that is just as strong."

Obama said his administration would do its part to expand opportunities to volunteer in local communities, boost programmes to serve in US aid agencies abroad, and would offer university tuition subsidies to students in exchange for civil service.

Obama, 46, also called for nearly 100,000 extra soldiers to relieve the strain on current US military deployments, but said the role of non-military organizations could help restore the country's sagging reputation abroad.

Prodding Americans to get involved in their own communities, Obama highlighted his own days as a community organizer in Chicago as some of his most formative years.

"Loving your country shouldn't just mean watching fireworks on the fourth of July," the Illinois senator said. "Loving your country must mean accepting your responsibility to do your part to change it." (dpa)