British police have apologized for having a mock suicide bomber shout the phrase "Allahu Akbar" before setting off an explosion during a terror response exercise.

Greater Manchester Police said in a statement Tuesday it had been "unacceptable" to use the religious phrase as part of the terror drill at a major Manchester shopping mall.

The Arabic phrase means "God is Great."

Police Chief Tony Lloyd said the use of the phrase could "undermine" strong community relations in the city.

Police said the mock operation was based on the style of attacks that had recently been used by the the extremist group ISIS. It was designed to test the response of emergency teams.

ISIS extremists have often used the phrase before attacking civilian targets.