A Greek prosecutor has begun an investigation into an allegation by a journalist, Thanasis Koukakis, who works for CNN Greece that his smartphone had been infected by surveillance software in an operation by the country's intelligence service.

A spokesman for Greece's EYP intelligence service told Reuters it had no comment on Greek media reports detailing this assertion.

The allegation comes as the European Union (EU) is beginning to follow the United States in taking a harder look at spyware merchants and the use of powerful surveillance software.

"A preliminary investigation has begun on the matter," the prosecutor, who declined to be identified by Reuters, added the probe would seek to determine whether there had been a breach of the country's telecommunications privacy legislation.