CNN has learned that Iran threatened the families of its World Cup soccer squad after the players refused to sing the country's national anthem at their opening game.

The source, who is involved in security for the World Cup, told CNN that the players were brought to a meeting with the Iranian Revolutionary Guard Corps after the first game.

They were told that if they didn't sing the national anthem, their families would be tortured.

The team prepared for their second match by singing the anthem.

A source told CNN that the team was being watched by dozens of revolutionary guard members and that they were not able to meet with players from other teams or anyone who was not part of their squad.

A source tells CNN that there are a lot of Iranian security officers in the country.

Iran sent hundreds of support actors to the first game in order to create a false sense of support and favor among the fans, according to a source.

The source said that Iran will send more actors into the thousands when it plays the US on Monday.

The death of a Kurdish woman in police custody has led to protests in Iran. Under the Iranian government's interpretation of Islamic law, Amini had to wear a hijab.

Thousands of people have been taken into custody for peacefully protesting. The United Nations said that around 300 people have died.

Iranian woman have removed their hijabs and cut their hair during protests.