Two Qld teens missing in separate cases

A 13-year-old girl missing for almost a month has been sighted in Queensland.

The Mackay girl was seen on Friday afternoon wearing blue jeans and a hooded jumper at McGills Road in Kalkie, a suburb of Bundaberg.

She is believed to be travelling with an older man in a white Holden Commodore and has been missing since April 29.

The man was also sighted separately in Bundaberg on Friday afternoon at a shopping centre wearing a black t-shirt with a white logo, black jeans, black sneakers and a grey hat.

The girl is Caucasian, about 170cm tall with a slim build, dark hair and wears pink glasses.

In a separate case, police are searching for a 14-year-old boy last seen in Brisbane's south on Monday.

The boy, who has not contacted his family since Monday, was last seen at Acacia Ridge and is usually with friends in the Logan area.