LOME, June 17 (Reuters) - Authorities in Togo are investigating a suspected outbreak of avian flu after the sudden mass death of poultry on a farm, the government of the small West African state said on Sunday.

A agriculture ministry statement cited by state media said test samples had been sent to a regional laboratory to determine whether the outbreak involved the highly pathogenic H5N1 strain, which was reported in neighbouring Ghana in May.

The investigation was focusing on a semi-industrial farm at Sigbehoue, about 45 km (28 miles) east of the capital Lome, where about 2,000 chickens out of a total stock of 3,000 had died in two days, the official government Website said.

It quoted agriculture ministry officials as saying the remaining birds had been destroyed and the farm sealed off.

If confirmed, the Sigbehoue outbreak would be the first bird flu case detected in Togo, a small nation on the Gulf of Guinea sandwiched between Ghana to the west and Benin to the east.

In May, Togo halted poultry imports from Ghana, which confirmed it had at least two outbreaks of H5N1 in farm birds.

Several countries in West Africa have detected outbreaks of the disease and the worst hit, Nigeria, reported sub-Saharan Africa"e;s only confirmed human death from H5N1 early this year.