WASHINGTON (AFP) - The United States has sent an additional 180 troops to the storm-ravaged Philippines for humanitarian assistance efforts, the Marine Corps said on Monday.

Four MV-22B Ospreys - aircraft that can operate in difficult environments - and three KC-130J Hercules planes headed to the disaster zones from Japan over the course of the afternoon and evening, according to a statement.

On board were some 180 marines and sailors tasked with helping a humanitarian assistance survey team on the ground in the wake of Typhoon Haiyan, which may have killed as many as 10,000 people as it flattened entire towns just days ago.

Some 90 marines and sailors are already in the disaster-stricken country for an assistance evaluation mission.

US marines who arrived in the city of Tacoblan earlier on Monday to deliver emergency supplies expressed shock at the devastation.

"Everything's destroyed," said Brigadier General Paul Kennedy, the commanding general of the Okinawa-based 3rd Marine Expeditionary Brigade.

Since 1990, the US government has responded to more than 40 disasters in the Philippines, according to the Pentagon.