Alliyah Montaque, 15, and Lina Bennacef, 16, were last seen on Wednesday, 13 April.
It is believed the girls are together and that they may be in the company of an older teenager who has links to south London.
Their disappearance is out of character and officers are growingly concerned for their welfare.
Anyone who sees the girls should call 999 immediately.
Anyone with other information about their whereabouts is asked to call 101 with the reference 6276/13APR.
Information can also be provided to Crimestoppers, anonymously, on 0800 555 111 or to the Missing People charity on 116 000.
Officers are also appealing to Alliyah and Lina directly to contact the police, or someone they trust, to let us know they are safe if they are able to do so.
