Published by pro-government outlet Fresh News, the court order stipulates that Kem Sokha, who was arrested in 2017 and accused of treason, remains under court supervision and forbids him from going overseas and conducting any political activities.
"We will not stop ordinary individuals coming in and out, we just cease rebels", national police spokesman Chhay Kim Khoeun told Reuters.
Sam Rainsy missed his self-declared deadline of returning to his home country on Saturday, Cambodia's Independence Day, and his further plans are not clear.
Deputy Prime Minister Sar Kheng denied on Facebook that the opposition leader was not allowed to return, saying Rainsy and his colleagues may re-enter Cambodia but will face justice if they do so.
Hun Sen, known over nearly 35 years in power as a wily and ruthless politician, has a history of employing divide-and-rule tactics against his opponents.
"Keep up the hope. We're on the right track", Mr Rainsy said in a message to supporters as he arrived at Kuala Lumpur International Airport.
Amnesty International denounced collaboration by Malaysia and Thailand to stop foreign-based Cambodian resistance figures from becoming home. "It is a due process in Cambodia", he said.
Rainsy fled to Paris in 2015 after a conviction for criminal defamation.
"We still continue to call for the drop of all charges and reinstatement of his political rights", Monovithya also wrote on Twitter. Malaysia allowed her to enter the country Thursday after detaining her for about 19 hours while questioning about her intentions.
"But the Royal Government of Cambodia has also announced the right to take legal action against any actions that attempt to undermine peace, social stability and security of the state".
Cambodians were prohibited from crossing from Poipet to shop in the Rong Klua market in Thailand, effectively shutting down the normally bustling exchange in Sa Kaeo province, according to a Thai Rath report.
The EU delegation in Phnom Penh made no immediate comment.
An opposition official in Thailand said plans to return on Saturday were abandoned.
She noted that at least 89 people have been charged with "plotting against the State" and at least 52 people have been arrested in 20 provinces-many in connection with voicing support for Sam Rainsy's planned return-bringing to more than 200 the number of cases of harassment, and judicial actions against CNRP members or supporters since the start of 2019.
More than 50 more people have been arrested in recent weeks since Rainsy said he planned to return home from self-exile in France to rally opposition to Mr Hun Sen.
Mr Rainsy said he would be in Malaysia for "a few days" meeting "like-minded friends" and would speak to parliamentarians on Tuesday.
His freedom to hold meetings appeared to mark a rapid shift in stance from Malaysia, which earlier this week detained and later released the Cambodian opposition party's vice-president, Mu Sochua, and two other officials.
"This must be Hun Sen, Cambodian dictator", who put pressure on neighboring countries.
"Malaysia deserves kudos from around the world", said Phil Robertson of US -based Human Rights Watch. "More governments in ASEAN need to emulate Malaysia if the bloc is ever going to rid itself of its reputation as a rights abusing club of recalcitrant dictators".
The opposition party announced in August that Sam Rainsy will return to Cambodia on November 9-the country's Independence Day-to lead a restoration of democracy, calling on supporters and members of Cambodia's armed forces to join him, but Hun Sen has labeled the plan part of a rebellion and has vowed to arrest the opposition leader on sight.
The party's dissolution was seen as a political ploy to ensure victory by Hun Sen's party in the 2018 general election by eliminating the only credible opposition group.