The extension would allow the Oceanic Viking, which has been moored on Bintan island since last month, to stay while a solution is found to an impasse that has seen the migrants refuse to disembark, Foreign Ministry spokesman Teuku Faizasyah told reporters.
"We have issued a permit for the Oceanic Viking to stay in Indonesian waters until Friday next week," Faizasyah said.
"Hopefully, the extension of the permit could be an incentive for Australia to speed up the negotiation process with the Sri Lankan migrants and come up with a resolution," he said.
The migrants were rescued by the Australians last month and brought to Indonesia by agreement between the two governments, but the ethnic Tamil Sri Lankans have refused to deal with the Indonesians and insist they be taken to Australia.
Australian media have reported that some of the migrants, who were rescued in Indonesia's search and rescue zone, had already been classified as refugees and had been living in Indonesia for up to five