Police in Costa Rica have arrested 11 people in connection with the murder of a Dutch couple at the beginning of this year.

Plantation director Hans Snelders, his wife Sita Dwahtal and a Nicaraguan worker were found dead on the teak plantation where they lived by another worker as he returned from holiday.

The couple lived in an isolated part of the country, south west of the capital San José. The murders are thought to have taken place around Christmas but were only discovered in January.

The 11 arrests were made after a shoot-out in the western province of Puntarenas and one of the men arrested required hospital treatment, news agency ANP said.

Police had always said the couple were killed in a robbery but other motives have not been ruled out.