COLOMBO, March 20, 2009 (AFP) - Australia on Friday called on Sri Lanka to present "credible political reforms" to end ethnic bloodshed and expressed grave concern over the worsening humanitarian crisis in the island's north.

Australian Foreign Minister Stephen Smith also asked Sri Lanka's Tamil Tiger rebels to lift all restrictions on civilians living in rebel-held areas amid allegations that the guerrillas are holding them as human shields.

"There can be no justification for preventing free movement of civilians from the conflict zone," he said in a statement sent here. "We encourage the Sri Lankan diaspora to add weight to this call to prevent further loss of
life."

"Australia again calls on the Sri Lankan government to put forward credible political reforms to engage Tamils and other minorities without delay," Smith said.

"A political solution that meets the legitimate aspirations of all Sri Lankans is essential for the long-term security and prosperity of Sri Lanka."

The minister said arrangements must be put in place urgently to allow the safe passage of civilians from the shrinking war zone, where government forces are leading their biggest ever offensive against the Tigers.

"As long as civilians remain in the conflict zone, both sides have an obligation to ensure that hostilities are not conducted in a way which endangers civilian life," he said.

The United Nations rights chief said last week that over 2,800 civilians have been killed since late January and both sides of the conflict may be guilty of war crimes.

Tamil Tiger rebels have been fighting for an independent state in the island's northeast. Their mini state was dismantled by security forces earlier this year with the capture of their political and military headquarters.

Sri Lanka's government pulled out of a Norwegian-arranged truce in January 2008.