(Adds details on protest in King of Prussia)

By Alex Dobuzinskis

Dec 20 (Reuters) - More than 1,500 protesters against police violence shut down part of the Mall of America in Minnesota on Saturday, resulting in about 25 arrests during the final weekend before Christmas as shoppers scrambled to buy gifts at one of the nation's largest shopping centers, officials said.

The protest and a smaller action at the King of Prussia Mall in Pennsylvania were the latest in a series of U.S. demonstrations in recent weeks over grand jury decisions not to charge white police officers in the killings of unarmed black men in Ferguson, Missouri, and New York City.

Police at the Mall of America in the Minneapolis suburb of Bloomington arrested about 25 demonstrators, mostly for trespassing and failure to disperse, said Bloomington police spokesman Commander Mark Stehlik.

The action organized by Black Lives Matter Minneapolis saw participants gather in a mall rotunda where some staged a so-called "die-in," said a participant Mischa Kegan, 30, who is an organizer with the group Community Action Against Racism.

At least 1,500 people took part, Stehlik said. Some protesters moved around the shopping center and chanted after the bulk of the gathering broke up, he said.

A representative from Black Lives Matter Minneapolis could not be reached for comment.

A Mall of America statement said stores were closed on the east side of the mall as protesters were cleared, but the shopping and entertainment complex was later fully reopened.

At another action on Saturday in King of Prussia, protesters staged a "die-in" at the community's shopping center outside Philadelphia, according to local television station WCAU. The NBC affiliate reported that more than 180 people took part.

A police dispatcher confirmed a protest took place at the King of Prussia Mall, the largest retail shopping space in the United States, and said demonstrators lay down on the ground but there were no arrests.

Last month, days after a St. Louis County grand jury declined to indict Ferguson, Missouri, police officer Darren Wilson in the shooting death of teenager Michael Brown, demonstrators targeted shopping centers in a number of cities on Black Friday, the day after Thanksgiving that typically ranks as the nation's busiest shopping day.

The protests on Saturday came as shoppers filled malls and department stores across the United States on the last weekend before Christmas.

(Reporting by Alex Dobuzinskis in Los Angeles; editing by Gunna Dickson)