A Spain-Portugal bid will provide strong competition for England
Russia has become the latest country to join England in declaring an interest in hosting the 2018 World Cup.
They now join a list that includes Australia, Qatar, the United States and joint bids from Belgium and the Netherlands and Spain and Portugal.
More bids are expected to follow, but countries must formally register their interest with Fifa by 2 February.
England are set to face stern competition with the joint Spain-Portugal bid among the favourites.
Spain hosted the World Cup in 1982 and the European Championship in 1954, while more recently Portugal beat Spain to host Euro 2004.
Spanish federation president Angel Maria Villar and Portuguese counterpart Gilberto Madail signed the agreement for a joint bid in Lisbon on Monday.
The two countries will now form a joint committee to take the project forward.
Russia's likely candidacy was announced by the Russian Football Union president Vitaly Mutko, who is also the country's sports minister.
"In the near future we are set to make our first move and ask Fifa for all the necessary documents to prepare a bid for the right to host the 2018 World Cup," said Mutko.
"This issue is very complicated and demands a big investment. But we will definitely make the first step of submitting an application."
Russia has never hosted the World Cup, although the former USSR did bid for the tournament in 1990, but lost out to Italy.
Fifa will consider bids to host both the 2018 and 2022 tournaments over the next two years.
Spain and Portugal bid will be among England's biggest rivals as the joint bid can expect support from the three South American representatives on Fifa's 24-man executive committee, who will decide a winner in December 2010.
Candidates must be able to provide up to 12 stadia with minimum capacities of 40,000 for group matches and 80,000 for the opening match and final.
Spain generally has the larger stadia and is expected to host most of the matches, although Portugal built seven new grounds and renovated three others for Euro 2004.
The 2010 World Cup will be held in South Africa, while Brazil will host the 2014 tournament.
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