A ferry with an estimated 50 people aboard has been missing for more than a week off the coast of the Pacific nation of Kiribati, rescue authorities said Saturday.

New Zealand’s Rescue Coordination Centre said it had sent a military Orion plane to assist in the search of an area of ocean approximately the size of Britain. The search is being led by Fiji.

Authorities said the ferry departed Nonouti Island bound for South Tarawa on Jan. 18. The journey of 240 kilometers (149 miles) was expected to take two days.

Senior Search and Rescue Officer John Ashby said the MV Butiraoi, a 17.5-metre (57-foot) wooden catamaran, was first reported missing to them late Friday.

He said the vessel underwent repairs to its propeller shaft just before leaving, which may have contributed to navigation problems. Ashby said people on islands and vessels along the planned route are being contacted to ask if they have seen the vessel.

Kiribati is a remote, impoverished nation of 33 atolls that is home to about 108,000 people.