Stockholm - Thirteen people in four European countries were Wednesday confirmed to have been infected with swine flu while 128 cases were confirmed worldwide, a European health agency reported.

The confirmed European cases were in Britain, Germany, Spain and Austria, Denis Coulombier of the European Centre for Disease Prevention and Control (ECDC) said.

"All were exposed outside the EU in Mexico," Coloumbier, head of the ECDC preparedness and response unit, said at a briefing.

"The cases in the EU tend to be young adults. They were exposed in Mexico and belong to the group of people who travel or abroad for vacation or business," Coloumbier added. "All the cases are mild as far as we know."

The confirmed cases outside the EU included 33 in Mexico, 64 in the United States, 13 in Canada, 14 in New Zealand and two in Israel.

Commenting on the first death of a young child reported in the US, Coloumbier said that it was expected, citing the death rates also caused by so-called seasonal influenza.

The victim who "resided in Mexico was transferred for medical reasons to Texas and that kid had an underlying condition that certainly contributed to the death," he said.

The ECDC with headquarters in Sweden began to operate in 2005, and groups the bloc as well as non-EU members Norway, Iceland and Liechtenstein.

"We really don't know just how severe this virus is, to what extent it will cause deaths," Professor Angus Nicoll, head of the ECDC's influenza programme, said.

Nicoll said that seasonal influenza also causes deaths, close to 1 per cent among people over 65.

He welcomed reports that the World Health Organization was set to name the virus that he preferred to call the "novel virus" as opposed to swine flu. (dpa)