Swedish tax officials say ABBA star Bjorn Ulvaeus owes $2.1 million for decades-old undeclared royalties from the supergroup's hits. Authorities suspect royalty payments to Ulvaeus were made to companies operating in foreign tax havens.

The Associated Press reports that this is the second time the Swedish Tax Authority has gone after the 61-year-old singer for allegedly unpaid taxes.

Last year, the statlig skatt samlaren (I think that's "tax collector" in Swedish, but I'm at the mercy of an online translator, so ... ) claimed Ulvaeus owed almost $13 million in back taxes, fees and interest on unpaid taxes related to contracts he signed before his 1984 move to England.

In the contracts case, Sweden eventually agreed to reduce the tax bill to around $9.5 million, but Ulvaeus appealed the case. It's pending. No response yet from the singer or any of his people on the royalties allegations.

Although the group last performed together in 1982, its continuing popularity is inexplicably (but obviously that's just me ...) evidenced by the musical Mamma Mia, a hit on Broadway and in touring companies worldwide, and the more than 370 million ABBA albums that have been sold.