RIYADH, Nov 15 (Reuters) - Saudi Arabia has culled 50,000 birds at a poultry farm near the capital of Riyadh, which were found to have a deadly strain of bird flu, Saudi media reported on Thursday.

An agriculture ministry statement carried by newspapers said the birds were culled at the farm in al-Kharj, 150 km (94 miles) south of Riyadh, after 1,500 birds died earlier this week.

The statement said it was not clear how the birds had become infected with the H5N1 virus. It gave no more details.

In March, Saudi Arabia said the deadly strain of bird flu had been discovered in peacocks, turkeys, ostriches and parrots at a house in the east of the kingdom and that an unspecified number of birds in the area had been culled.

In February, Saudi Arabia lifted bans going back to 2004 on poultry imports from 42 countries.

Previously, bird flu was reported as having affected several falcons in the kingdom in 2006. (Reporting by Andrew Hammond; Editing by Chris Johnson)