Cambodia's opposition leader has received a royal pardon, paving the way for his return from self-imposed exile for elections.
The application for the pardon was made by Prime Minister Hun Sen, who is expected to win the 28 July polls.
Mr Rainsy, who has been living in France, was sentenced to 11 years in jail in absentia, for charges including altering public documents.
The opposition leader described the move as a "small victory".
It came after Mr Rainsy wrote to Cambodian King Norodom Sihamoni in June requesting a pardon and pledged to return to Cambodia for the elections.
Cambodia has also come under pressure from the US to allow Mr Rainsy to return "without fear for his personal safety or incarceration".
On Wednesday, a number of US lawmakers said that aid to Cambodia should be cut unless the polls were free and fair.
Hun Sen, one of the world's longest-serving prime ministers, has been in power in various coalitions since 1985.
In an interview with AFP news agency, Mr Rainsy said: "It is a small victory for democracy that the leader of the opposition be allowed to be in the country during election campaigning and on election day... much more remains to be done."
Mr Rainsy has been living in France since 2009, after he was charged with crimes he said were politically motivated and stripped of immunity from prosecution.
In 2010, he was sentenced in absentia to 10 years in jail after being found guilty of manipulating a map to suggest Cambodia was losing land to Vietnam.
King Norodom Sihamoni granted the pardon on Friday after receiving the request from Hun Sen, reports said.
Cabinet spokesman Phay Siphan said Hun Sen had arranged the pardon "for the sake of the country and in the spirit of national reconciliation".
"Sam Rainsy is free now; he can come back to Cambodia. We welcome him back."