Most of the thefts are said to have occured at Lisbon shopping centres and train stations, police added and come as the result of an investigation launched September last year.

The trio, two men and a woman, are said to between 51 and 57 years old, and were arrested after a major operation on Friday in three areas of the capital, including the downtown area and stations which are popular with foreign visitors.

Police said the gang almost always targetted tourists, and would either follow them from foreign currency exchange venues in shopping centres or would prowl major train stops such as Entrecampos and Oriente.

Police sources the three would often volunteer to assist tourists, with the older man, well dressed, well-spoken and always carrying a briefcase, usually providing the unsolicited help while his accomplices would seize the opportunity to steal from their unsuspecting victims.

The three were arrested after they robbed a foreign national who was travelling from the busy Entrecampos station to the Algarve, making off with 65 Canadian dollars, 141 US dollars and 875 euros.

The gang had already been detained in the past and were currently on parole, having to appear at their local police stations on a fortnightly basis.