Officers from Operation Elveden, the Met's probe into alleged illegal payment to police and public officials, arrested two more people this morning.
A man and woman were arrested at their home address in north west London at 6am, according to a statement from the Met.
The 50-year-old man is an employee of HM Revenue and Customs and was arrested on suspicion of misconduct in a public office, contrary to common law and suspicion of corruption under the Prevention of Corruption Act 1906.
A 43-year-old woman was also arrested at the address on suspicion of aiding and abetting misconduct in a public office and suspicion of money laundering offences under Section 328 of the Proceeds of Crime Act 2002.
Both are being questioned at a central London police station, bringing the number of arrests in the Elveden probe to 29.
The Met said: 'Today's arrests are the result of information provided to police by News Corporation's Management Standards Committee.
'They relate to suspected payments to a public official and are not about seeking journalists to reveal confidential sources in relation to information that has been obtained legitimately."