STORY: It's believed most of the 78 people on board were trying to get to Australia.
Sri Lanka is currently suffering the worst economic crisis since its independence.
Many people have attempted to leave the country and long queues can be seen at passport offices.
The COVID-19 pandemic hammered the tourism-reliant economy and slashed remittances from overseas workers.
The financial crisis has been compounded by large and growing government debt, rising oil prices and a seven-month ban on importing chemical fertilizers last year that damaged farm output.
Headline inflation in the country of 22 million hit 54.6% last month, and the central bank has warned that it could rise to 70% in the coming months.
Sri Lanka's president and the cabinet will make way for a unity government, the prime minister's office said on Monday, after tens of thousands stormed the official residences of both men, enraged by the island's worst economic crisis in decades.