Guerrero state officials in Mexico made the announcement Sunday but declined to say how many suspects were in custody.
Gov. Angel Aguirre said two of those detained were also were being investigated in connection with another rape case. He said the two had been identified by victims in that case, but he added that no identifications had been made by victims in the rape of the Spanish women.
About 40 people briefly blocked the road to Acapulco's airport, saying five of their relatives had been wrongly detained in the case. They charged that the men are being made scapegoats.
"It's been 48 hours that our family hasn't seen them. We know nothing about them. One is a nephew and one is my brother," said one of the protesters, who gave her name as Flor Silva.
Authorities declined to comment on whether the protesters' relatives were among those detained in the tourist rape case. The state public safety secretary, Guillermo Jimenez, persuaded the protesters to end the road blockade in return for being allowed to meet with their relatives.
State government spokesman Pedro Julio Velez said the suspects in the rape of the Spaniards were detained by the federal Attorney General's Office and taken to Mexico City for interrogation. Spokesmen for the federal prosecutor did not answer calls seeking comment.
The governor said victims in a separate rape case had identified two of the detainees as being their attackers
The Feb. 4 attack on the Spaniards began when a band of masked gunmen broke into a beachfront home before dawn. The attackers tied up the six men at the house, and then raped the six Spanish women there. A seventh woman, a Mexican national, was not harmed during the hours-long assault.
The incident shocked people across Mexico and beyond, and was a new blow for Acapulco, which has been the scene of violence in recent years attributed to fighting among rival drug gangs. Tourism industry executives have worried that the attack could hurt business in other Mexican resorts.
Based on reporting by The Associated Press.