Ten more birds had tested positive for the deadly H5N1 strain of bird flu in Germany, raising the number of cases to at least 13 in the country, a government spokesman said on Thursday.

The ministry for agriculture and the environment in the Baltic coast state of Mecklenburg-West Pommerania said that nine swans and one goose from a group of 40 dead birds tested on Thursday were infected.

The ten birds were found near the site where two other dead swans and a goshawk had been confirmed as carrying the virus on Wednesday.

Earlier on Thursday, Agriculture Minister Horst Seehofer warned that more cases of bird flu may be detected Germany, home of Europe's largest economy.

Chancellor Angela Merkel said in a television interview on Thursday evening that the government had spent months preparing for an outbreak of avian flu and was now in a position to do everything necessary to contain it.

"There's no reason for a panic reaction but I would advise people to be careful," Merkel told ZDF television.

The German government had ordered poultry to be kept indoors from Feb. 17 through the end of April in an effort to lessen its spread.

All bird markets and exhibitions have been banned in Germany, where scientists had discovered no clue as to where the dead birds had caught the virus.

Bird flu has spread across Europe, with confirmed cases in Hungary, Greece, Italy, Ukraine and Romania, and suspected ones in Austria and Slovenia.

At least 91 of the 169 people known to have been infected with the H5N1 strain have died, mainly in Asia, according to the World Health Organization.

Source: Xinhua