Putin will fly to Zurich if Russia wins bid
"If Russia's bid to host the World Cup wins, the Prime Minister will be ready to fly out to Zurich," the spokesman told local media on Thursday.
The announcement will be made at 1500 GMT.
Putin, who was credited with helping win the 2014 Winter Olympics hosting rights for Sochi, was due to be on a domestic engagement in the Russian Baltic enclave of Kaliningrad on Thursday but his plane was turned back because of bad weather, Reuters sources said.
On Wednesday, Putin had criticised the voting process, saying his country had faced "unscrupulous competition" in the bid to host the World Cup.
Putin, in an apparent blast at British media, said FIFA officials were being smeared and called on other political leaders to follow his example and stay away from FIFA's vote on Thursday to choose the hosts of the 2018 and 2022 World Cups.
"We have unfortunately witnessed a campaign against members of the FIFA executive - filth and compromising material has been poured over them. I see this as unscrupulous competition ahead of the vote," he told ministers in Moscow on Wednesday.
"I would have liked to have gone myself but under these conditions, I have decided to refrain from travelling out of respect for the members of FIFA, the members of the FIFA executive, so that they can make a decision calmly without any pressure from the outside.
"Russia wants and hopes and has the ability, including financial, to host this largest of tournaments. If we are given the chance we will do this in the best possible way."
Russia is one of three European bids - the others are England and joint campaigns from Spain and Portugal and from Netherlands and Belgium - competing for the right to stage the potentially lucrative 2018 tournament.