A 32-year-old woman arrested by Scotland Yard officers investigating inappropriate payments to police and public officials is understood to be The Sun newspaper's defence editor, Virginia Wheeler.
She is arrest number 23 in Operation Elveden and is being held at a south London police station on suspicion of corruption under the Prevention of Corruption Act 1906.
Wheeler is thought to have returned to Britain from overseas for arrest by appointment, as the police want to question her.
This is the eleventh Sun journalist to be arrested.
Elevden was originally set up to probe illegal payments to police officers by journalists, but it has been expanded out to all public officials.
It was launched in July by the Metropolitan Police alongside two other operations, Weeting and Tuleta.
Weeting is looking into phone hacking at Rupert Murdoch's News International, while Tuleta is looking into computer hacking by journalists.