A British government minister has said Costa Rican police are responsible for preventing police co-operation in the search for missing journalist Michael Dixon.

"Any request from the Costa Rican authorities for assistance would need to come from the OlJ [the Organismo de Investigacion Judicial, a part of the interior ministry] ... An invitation has not been forthcoming," UK minister Jeremy Browne said in a letter to the Dixon family dated 28 June.

Browne highlighted that the OIJ position goes against the words of Costa Rica foreign minister Rene Castro, who "has indicated that he would welcome the help of the British police to solve Michael's case."

Browne ruled out putting diplomatic pressure on Costa Rica in the same way that Prime Minister David Cameron recently urged Portugal in the case of Madeleine McCann.

"The involvement of the Metropolitan Police Service in the McCann case is to review the available material. However, the case remains filed in Portugal and while the search remains active we are unable to comment on any specific details of the investigation," said UK minister Jeremy Browne.

Michael Dixon vanished after leaving his hotel room in Tamarindo, Costa Rica, on 18 October 2009. The OIJ has given up looking for him after first claiming he drowned on the basis of no evidence.

"This case will never be solved unless the Metropolitan police gets involved. [Foreign minister] Castro himself said the OIJ is not up to the job," Michael's brother, David Dixon said.

"We are being fobbed off with red tape on all sides. Is Michael a second class British citizen compared to the McCanns?"

Over a dozen EU, Canadian and US nationals have been either murdered or have vanished in Costa Rica in the past two years. Most of the cases go unsolved.

The Dixon family will on 19 July mark Michael's 35th birthday.