Four men who were allegedly hired to kill nightclub owners in Athens for refusing to pay money for protection have been arrested, police said yesterday. Three Albanian nationals, aged 38, 36 and 22, were arrested along with a 44-year-old Greek man on suspicion of three counts of attempted murder. The hits, each costing 30,000 euros, were apparently ordered by a convicted mobster currently serving a jail term. The prisoner, who was not identified, ran a protection-for-payment racket and demanded the murders of nightclub owners and businessmen who refused to participate in it. The protection fee demanded ranged between 600 to 1,200 euros per month. Prostitutes and brothel owners were also involved in the racket over the last four years. Police said they found bullets and two guns in the home of the Greek suspect. Authorities are searching for another four men thought to be involved in the racket.