PHNOM PENH, Oct 13 (Reuters) - The United States on Wednesday accused Cambodia of lacking transparency about Chinese construction activities at its biggest naval base, and urged the government to disclose to its people the full scope of Beijing"s military involvement. The Center for Strategic and International Studies (CSIS) on Wednesday made public what it said were satellite images showing construction in August and September of three new buildings and the start of a new road. U.S. embassy spokesperson Chad Roedemeier in a statement said that any foreign military presence at Ream would violate Cambodia"s constitution and undermine regional security. "The government of Cambodia has not been fully transparent about the intent, nature, and scope of this project or the role of the PRC military, which raises concerns about intended use of the naval facility," he said, referring to China. PHNOM PENH, Oct 13 (Reuters) - The United States on Wednesday accused Cambodia of lacking transparency about Chinese construction activities at its biggest naval base, and urged the government to disclose to its people the full scope of Beijing"s military involvement. The Center for Strategic and International Studies (CSIS) on Wednesday made public what it said were satellite images showing construction in August and September of three new buildings and the start of a new road. U.S. embassy spokesperson Chad Roedemeier in a statement said that any foreign military presence at Ream would violate Cambodia"s constitution and undermine regional security. "The government of Cambodia has not been fully transparent about the intent, nature, and scope of this project or the role of the PRC military, which raises concerns about intended use of the naval facility," he said, referring to China. "The Cambodian people deserve to know more about the project at Ream and to have a say in this type of military agreement, which has long term implications for their country." Cambodia"s ties with the United States have frayed in recent years over U.S. allegations its ruling party is persecuting its opponents, and concerns about China"s growing influence. A year ago, Cambodia said it had razed a U.S.-funded facility at the Ream naval base to allow for further expansion. The United States said Cambodia had a year earlier turned down its offer to repair the base. Cambodia has repeatedly denied reports that it is planning to let China place its forces at the facility. Such a move would be significant for China in a region where the United States has for decades maintained a regional presence through bases it once operated or joint exercises in countries like Thailand and the Philippines. Phay Siphan, Cambodia"s government spokesman, said Chinese construction at Ream was part of its development assistance. "Our port is open to all when the construction is finished," Phay Siphan said, adding that China was not building a facility for its military. "If there are other friends who want to help constructing, we allow and when the construction is finished, we welcome all countries to use it," he said.