The nation's largest Muslim advocacy organization has filed a complaint with police in a Las Vegas suburb, saying seven Muslim men from southern California were detained and told they were acting suspiciously while praying in a shopping center parking lot.

The Council on American-Islamic Relations said Friday it filed the complaint this week against the Henderson Police Department because it did not understand what was suspicious about the men.

"Our main concern is the police department looking at praying and the way they looked as probable cause for investigating those men," said CAIR spokeswoman Munira Syeda. "They did nothing illegal."

Henderson police spokesman Todd Rasmussen said the complaint was received and internal affairs would investigate, but he declined comment on the incident.

Rasmussen said the department would inform the group of the outcome of its complaint, but said it did not have a timeline for an investigation.

The group says the men, whom it identified as being of various ethnic backgrounds including Middle Eastern and south Asian, were performing one of five required Muslim daily prayers in the lot while stopped to buy gas and food Dec. 20 during a roadtrip.

As they returned to their car, they were stopped by three officers and kept for about 40 minutes while three officers checked their backgrounds and searched their car, Munira said.

Munira said the men were not blocking traffic or preventing other cars from parking.

A CAIR attorney said in a statement that the group was seeking discipline against the officers involved, changes to officer training and compensation for the emotional distress of the men.

"The scope and length of the stop was not reasonable under the circumstances, nor did it serve any legitimate investigative purpose," CAIR lawyer Ameena Qazi wrote in a letter to Henderson police.