(Reuters) - The number of foreign tourists killed in Wednesday's attack on the national museum in Tunisia has risen to 20 from 17 dead, Tunisia's health minister said on Thursday.

Three Tunisians also died in the attack.

Two gunmen opened fire on the Bardo museum in Tunis on Wednesday, killing tourists from Spain, Poland, Japan and Colombia, among other nationalities, in the worst attack in more than a decade in the North African country.

(Reporting by Tarek Amara; writing by Patrick Markey)