Four of those countries referred to by the US officials have privately said that they are "committed" to accepting prisoners already cleared for release, while five others are considering whether to take detainees, according to the newspaper.
An agreement by European nations to accept Guantanamo detainees would provide a boost to Obama in his efforts to close the prison by January next year.
The prison camp is holding 229 inmates designated "enemy combatants" by the previous US administration of George Bush during its so-called "war on terror".
About 80 of those detainees have so far been cleared for release.
Should more European nations forge an agreement with the US to resettle prisoners, it could dampen US opposition to transferring the remaining inmates to a facility on the US mainland, the newspaper said.
Five EU states – Portugal, France, Ireland, Italy, and Spain – have already publicly given their assent to accept detainees to their mainland or overseas territories.
However, the transfer of four Uighur detainees from Guantanamo to Bermuda, an overseas territory of Britain, could yet be over-ruled by London on the grounds that the US and Bermuda did not inform it of the deal.
In addition to the EU states that have privately committed to take Guantanamo inmates, Australia and Georgia have held "positive talks" with the US on accepting detainees, the US officials told The Washington Post.
The Obama administration has also approached some South American nations and is planning to appeal to others as well as countries in the Gulf, former Soviet republics and the Balkans, the paper said.
Obama, earlier this year, decided to go ahead with prosecuting some Guantanamo detainees in military commissions, while trying some others in US federal courts.
Human rights groups say that detainees' legal rights are limited through the military commissions process, given that the Pentagon decides on which lawyers will defend those in front of the commission.