Cambodian guerrillas have attacked northwestern government positions in a major offensive to protect U.S.-funded development programs, officials said Tuesday.

More than 2,000 troops of the Khmer People's National Liberation Front and fighters loyal to Prince Norodom Sihanouk began attacking positions around the district capitals of Svay Chek and Phnom Srok in Battambang province Monday, Liberation Front spokesman Ok Serei Sopheak said.Western diplomats in Bangkok said the offensive was designed to cut supply lines and extend what the guerrillas call their "liberated zone" to safeguard the American-backed development efforts. U.S. officials have said long-range artillery fired by the Vietnamese-backed government had been hitting the area.