PHOENIX (AP) _ Police arrested four people as they continued to unravel a bogus airline ticket ring that allegedly sold millions of dollars of stolen tickets by advertising discounted fares in national publications.

''Every major airline in the world is a victim in some fashion,'' said Capt. Tim Black, head of the police organized crime bureau. ''These individuals put together a major conspiracy by knowing how to access airline computers to put travel itineraries in the computer system.''

Investigators believe at least $7 million in airline tickets were stolen, some during burglaries of travel agencies, Black said.

Arrested Thursday at their Phoenix-area homes were Jurgen Thomos Steinmetz, 31; Rolf Grosse Heitmeyer, 37; his wife, Annedore Dore Heitmeyer, 35; and Karl Heinz Bersuch, 37. Police said the Heitmeyers and Bersuch are citizens of West Germany.

They were booked into the Maricopa County Jail for investigation of conducting an illegal enterprise, conspiracy to traffic in stolen property trafficking in stolen property, felony theft, money laundering and fraudulent schemes.

Steinmetz was being held on $1 million bond, Bersuch on $411,000, Rolf Heitmeyer on $343,000, and Mrs. Heitmeyer on $274,000.

Police also seized about $80,000 in cash, five vehicles, two homes and their contents, all of which were believed to have been purchased with the proceeds of the stolen-ticket operation, Black said.

Police said more arrests are possible.

The operation was based in Phoenix, but also had offices in Honolulu and Frankfurt, West Germany, police said. They would not say whether any of those arrested had worked for an airline.

Police became aware of the operation in June after a Los Angeles woman called to complain about a discount airline ticket she had purchased from a Phoenix travel agency that had advertised in a national publication. The undisclosed airline had rejected her ticket because it was listed as stolen.

The ads offered ''guaranteed lowest fares'' on international destinations, including Concorde flights, and listed a toll-free number.

A majority of the tickets apparently were accepted by the airlines, Black said.

An initial investigation in June resulted in the arrests of two Phoenix- area men - Prem Singh, 42, and Vijayant Shishodia - and the seizure of $50,000 in cash.

Singh remained in the county jail Thursday under $137,000 bond, officials said. He is charged with fraudulent schemes and is scheduled for a pre-trial conference on Aug. 31 in Maricopa County Superior Court.

Shishodia has been released from jail and his status was not known, officials said.

Black said the ticket operations continued as ''strong as ever'' after Shishodia and Singh were arrested.

1029EDT