A British couple's trip of a lifetime, sailing around the world on a yacht called Mr Bean, ended in horror after pirates allegedly killed the husband, tossed his body overboard and then tied his wife up in a cabin.

The attack occurred in the Malacca Strait, the body of water notorious for piracy, running between mainland South-East Asia and Indonesia.

Malcolm Robertson and his wife Linda on their Mr Bean adventure before pirates struck.

British reports say three Burmese men boarded the $632,000 boat, attacked 64-year-old Malcolm Robertson with a hammer, and might have slit his throat before they threw his body into the sea on Monday.

His wife, Linda, was tied up but wriggled free and called for help after the pirates left the boat in a dinghy.