LONDON — Former News International executive Rebekah Brooks and her racehorse trainer husband, Charlie, were arrested Tuesday in dawn raids that also netted four other suspects in the spreading phone hacking scandal.

Police said the six people were arrested on suspicion of conspiracy to pervert the course of justice. The charge is an indication that investigators may be focusing on a possible cover-up of the scope of phone hacking rather than the illegal hacking itself.

It was the most arrests in a single day since “Operation Weeting” – as the police investigation into phone hacking is known – began arresting reporters, senior news executives, police officers and others suspected of criminal acts.

The early morning police swoop brought the scandal to Prime Minister David Cameron’s immediate social circle. Cameron has said Charlie Brooks, Rebekah Brooks’ husband, was a longtime friend.

The scandal began in 2005 with the revelation that tabloid reporters had broken into the voicemail systems of aides to the royal family. It mushroomed last summer with the revelation that hacking had been widespread at Rupert Murdoch’s News of the World tabloid, which has since been shut.