Michael Asher, from Maidenhead, has not been seen since he boarded a train to Poole on 31 March.
It was later established that the 82-year-old was travelling around Dorset on buses, and police recently stated that he may have links to Jersey.
Appeals have been issued by Thames Valley Police, Dorset Police, the States police and missingpeople.org.uk.
He is described as white, 6 ft tall and of slim build.
In a statement on their website, the States police said: ‘Berkshire police are currently concerned for the welfare of missing person Michael Asher who has possible links to Jersey.
‘If anyone has any information relating to Michael’s whereabouts could they please contact either Berkshire police or States of Jersey Police on 612612.’
