By Jan Wolfe

Oct 29 (Reuters) - A federal appeals court on Thursday said Minnesota's plan to count absentee ballots received after Election Day was illegal, siding with Republicans in the battleground state.

In a 2-1 decision, the U.S. 8th Circuit Court of Appeals said the deadline extension was an unconstitutional maneuver by the state's top election official, Minnesota Secretary of State Steve Simon, a Democrat.

The appeals court said Minnesota election officials should identify and set aside all absentee ballots received after Nov. 3.

"Simply put, the Secretary has no power to override the Minnesota Legislature," the court's majority wrote.

A spokeswoman for Simon did not immediately respond to a request for comment.

Minnesota law requires that absentee ballots be received by Election Day. But that deadline was extended through a settlement Simon reached with a citizens group that sued earlier this year.

Under that settlement, which was approved by a judge, state election officials could count ballots received until Nov. 10 as long as they are postmarked by Nov. 3.

The settlement said if a mailed ballot were missing a postmark, election officials should presume it was mailed by Nov. 3 unless evidence showed otherwise.

Minnesota Senator Amy Klobuchar, a Democrat, said on Twitter that because of the "last minute" change voters in the state should vote in-person or take mail-in ballots directly to a ballot box.

"In the middle of a pandemic, the Republican Party is doing everything to make it hard for you to vote. Stand up for YOUR rights," Klobuchar said. (Reporting by Jan Wolfe Editing by Noeleen Walder and Tom Brown)