A Sri Lanka government minister says the Cabinet has approved setting up an office to learn the fate of several thousands of people who went missing during the civil war the ended seven years ago.

The statement from the foreign minister on Thursday says the "need to set up such an office is particularly acute as Sri Lanka has one of the largest caseloads of missing persons in the entire world" and the measure will help families discover the fate of their loved ones and the circumstances under which they went missing.

The office will come into effect when the necessary laws are passed by the Parliament, the ministry says.

More than 20,000 complaints on missing persons have been received.