In a two-page article published by the Spanish El Pais newspaper on Sunday, the Spanish government effectively accused Gibraltar of helping to facilitate money laundering and tax evasion through its apparent reticence when dealing with Spanish requests for assistance in fraud and fiscal investigations.

According to the report, the Spanish government found the Gibraltar police force generally cooperative in criminal investigations, if in an "underhand" sort of way.

However, it added that this cooperation tends to dry up when Spanish authorities request information about Gibraltar-based companies, banks and insurers.

The report claimed that there are 28,000 companies, 28 legal firms and 115 lawyers registered in Gibraltar, but that most of these are operating outside the control of the financial authorities. It also suggested that Gibraltar's popularity as a domicile for global e-gaming firms "worries the experts in the fight against the laundering of dirty money".

While relations between Spain, the UK and Gibraltar have improved somewhat since the formation of the Tripartite Forum in 2006, which has addressed some contentious issues, including as border control, Spain suggests that Gibraltar hides behind its colonial status in relation to the UK, which retains control over certain aspects of policy in the Rock.

El Pais claimed that it had passed on a set of questions to Gibraltar's Financial Services Commission and Financial Intelligence Unit, but that these had been ignored after being referred by them to the government.

Gibraltar's Chief Minister, Peter Caruana dismissed the Spanish allegations, telling the UK's Daily Telegraph newspaper that: "If the Spanish government is saying that the Gibraltarian authorities are not cooperating with Spain in the way we cooperate with other countries, then that is simply untrue."