Young American tourist missing in Cairns

Relatives of a young American tourist missing in Cairns say they haven't seen the 18-year-old for almost two weeks.

Marina Sanchez was last seen on January 10 when she left the Bentley Park home where she had been staying with a family while on holiday in north Queensland.

Authorities believe she may be staying somewhere else in Cairns and police are urging anyone who can help find her to contact them.

She is described as being of Caucasian appearance, about 165cm tall, with a tanned complexion and short dark brown hair and brown eyes.