The Cambodian Foreign Affairs Ministry had ordered a Jan. 1, 2011, close date for the site.
They were sentenced to 18 months in prison and a $250 fine in Siem Reap provincial court last week.
Such exercises have become more common between the two countries, with a gradually thawing of ties following Sept. 11, 2001.
The conflict resolution centers are geared to help the poor, women and minorities.
The government has said the incident was an unforeseeable accident and that no one will be punished.
The Chinese Foreign Ministry said on its website Hun Sen would pay an official visit Dec. 13 through Dec. 17.
Prince Norodom Ranariddh, who returned to his party this week, is seeking cooperation with both Funcinpec and Human Right Party.
Cambodian officials say they expect Hun Sen to sign even more deals with China on this visit.
China has made great economic strides since the collapse of the Soviet Union, posting double-digit growth.
In a December report, OSJI says donors can push harder for wider indictments and great participation by leaders.