Police spokesman Ajith Rohana said that 41 people were arrested in the eastern town of Vakarai, 280 kilometres east of Colombo, as they were making preparations to board a boat.
A woman and two children were among those arrested.
The police had separately arrested two more people for providing them with transport.
In past several weeks the police arrested scores of people including Pakistanis and Afghans who were lodged in Colombo with the aim of making illegal travel to Australia.
The Sri Lankan Navy has stepped up its surveillance in coastal areas to prevent illegal migration.
Australian authorities are alert on the surge in the number of Lankans asylum seekers reaching the country by boat.
In the first half of 2012, 1,346 asylum seekers claiming to have come from Sri Lanka have arrived in Australian territory, more than six times the 211 figure recorded in 2011, Australian authorities said.
