Long Sokunthy, 42, represents some 300 people who are locked in a long-running land dispute with a local tycoon.
Foreign Minister Taro Kono said that Tokyo would help Cambodia with free and fair elections, according to a spokesman for his office, Norio Maruyama, who confirmed that Japan would supply ballot boxes for the July polls.
Cambodia National Rescue Party (CNRP) was dissolved by Supreme Court last November at request of PM Hun Sen's government, which alleged it was plotting to take power with the help of US.
Local nongovernmental groups also invited to monitor July vote ruling party is expected to win because main opposition party was dissolved.
The 85-year-old American academic was given the Award for Distinguished Contributions to Asian Studies for his extensive body of scholarly work on Cambodia’s history, politics and culture.
The exhaustive study raises alarm about future hydro dams on the Mekong River.
The Mekong River Commission is meeting in Siem Reap province this week to discuss alternative energy solutions, large-scale Chinese investment, and governance issues.
The local authority has set an April 25 ultimatum for the Chong people to dismantle their community headquarters in the district they are not officially recognized as an indigenous group.
International delegates are required by law to be invited to observe Cambodian elections.
Record producer, Ian Brennan, and his wife Marilena Delli, a photographer and documentary filmmaker, are on a quest for the unknown and unfamiliar.
On Wednesday, regional governments met in Siem Reap for the third Mekong River Commission (MRC) summit.
The claims come more than two years after the government passed a controversial law regarding the conduct of non-governmental organizations in Cambodia.