Rihanna will be monitored by German police after she shared photographs of herself smoking marijuana.

The singer posted several pictures on Instagram at the weekend and one features her posing with two huge suspicious looking cigarettes in Amsterdam. In the caption on this photo she wrote '#LegalizeIt', apparently referring to the legalisation of marijuana.

Her concert tour is now moving from Holland to Germany where local authorities will not tolerate drug use.

'We're going to keep a close eye on her scene and her surroundings,' a police investigator in Cologne, Germany, told the Bild newspaper. 'We've noted what she made public on the Internet.

'Saying things like 'legalise it' isn't punishable, but if she encourages the use of drugs, that will have consequences,' the insider added.

Rihanna will perform in Cologne on Wednesday night.

The star has made little secret of her stance on cannabis.

She stepped out in the Dutch city sporting a T-shirt with a cannabis leaf logo emblazoned on it.

Her latest Instagram posts have been the subject of some controversy, with Daily Mail writer Liz Jones labelling her a 'poisonous pop princess.' She also said Rihanna promotes 'drug-taking, drinking and the sort of fashion sense on stage that surely invites rape at worst, disrespect at least'.

The singer hit back at the columnist, calling her a 'sad sloppy menopausal mess' and insisting she had no desire to be a role model.