LONDON (Bloomberg) ? Ship Finance International Ltd., owner of most oil tankers operated by Frontline Ltd., agreed to buy a rig for $185 million from Consafe Offshore AB and lease it back to the company for 30 years.

Consafe, based in Gothenburg, Sweden, has the right to buy the rig back after ten years, Hamilton, Bermuda-based Ship Finance said.

Ship Finance will assume ownership of the rig this quarter, once it has finished being upgraded, the company said.

"By this transaction we can demonstrate that Ship Finance's structure also works in the offshore sector in addition to the marine sector," Tor Olav Troim, the chairman of Ship Finance, said.