A magistrate court in Galle had on March 9 issued an order preventing Gotabhaya - the powerful defence secretary under his brother's administration - and three others from leaving the country until the conclusion of investigation.
The court also impounded their passports, police said.
In January, shortly after the defeat of the President Rajapaksa, a ship carrying 12 container loads of weapons was discovered in Galle.
The ship was carrying over 3,000 automatic weapons, including machine guns.
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The security firm has said its floating armoury was legal and authorised by Gotabhaya.
The private company - Avant-Garde Security Service - which maintained the armouries had provided security to ships against the Somali pirates.
It was alleged that the Sri Lanka Navy had lost income due to the floating armouries maintained by the company.