Samoan authorities warned Friday that anti-vaccine propaganda would not be tolerated, after a social media campaigner was arrested for opposing a mass immunisation drive aimed at containing the Pacific nation's deadly measles epidemic.

At least 63 people, mostly children, have died since the outbreak began in mid-October, with the crisis blamed on so-called "anti-vaxxers" convincing parents that immunisations were dangerous.

Samoa was on Friday enduring its second day of a lockdown as government and aid workers spread out across the nation of 200,000 people to vaccinate as many as possible.

But Communications Minister Afamasaga Rico Tupai said anti-vaxxers spreading conspiracy theories were hindering the unprecedented public health mobilisation.

"The anti-vaxxers unfortunately have been slowing us down," he told TVNZ.

"We've had children who have passed away after coming to the hospital as a last resort and then we find out the anti-vaccine message has got to their families and that's why they've kept these kids at home."

He warned anti-vaxxers: "Don't get in the way, don't contribute to the deaths".