Italian health authorities on Friday lifted a ban on the sale of flu vaccines made by Swiss pharmaceutical giant Novartis, saying that tests had shown they were not a health risk.

"The decision was made possible due to in-depth checks which were carried out as a precaution to protect public health," Italy's public agency for pharmaceuticals AIFA said in a statement.

Italy's health ministry last month ordered a ban on Aggripal, Fluad and Influpozzi after white particles were seen in syringes carrying the vaccines.

Austria, Canada, Germany and Switzerland subsequently also ordered temporary bans although some have since been lifted.

Novartis has said it is confident on the "safety and efficacy" of its vaccines.