President Nguyen Minh Triet, center, waves upon his arrival at the Phnom Penh International Airport in Phnom Penh

Vietnam's President Nguyen Minh Triet has begun a three-day visit to neighboring Cambodia.

The visit is Mr. Triet's first trip to Cambodia as Vietnam's head of state and follows an exchange of high-level visits last year.

A group of Cambodian Buddhist monks protested Tuesday outside the Vietnamese embassy and called for the visiting president to allow greater religious freedom in Vietnam. Riot police protected the embassy.

The two countries hope to boost cooperation in transportation, health care, and electricity. Trade between Vietnam and Cambodia has increased by more than 30 percent a year for the past decade, reaching 900-million dollars in 2006.

Last December, the prime ministers of Vietnam, Cambodia, and Laos met to discuss joint development in the poor and remote area where they share borders. They would like to create a development zone and attract Japanese investment.