Eduard Planells, ministry delegate for the northeastern province of Barcelona from 2004 until last month, was arrested along with four other people, said the police official. He spoke on condition of anonymity as he was not authorized to be publicly identified.
The private news agency Europa Press cited sources close to the investigation as saying Planells was suspected of facilitating work and residency permits for Russian Mafia gang members.
The arrests were ordered by Spain's anti-corruption attorney's office as part a probe into Russian gangs that has led to some 40 arrests and the freezing of dozens of bank accounts over the past two years.
Planells left the ministry to begin working with Spain's telecommunications regulator, which is based in Barcelona.
Two of the other four people arrested also worked in the Interior Ministry's department in Barcelona, the police spokesman said.
The discovery of the submarine has unveiled a few "inconsistencies." For example, how can one explain the fact that the sub was found where it needed to be searched for from the start?
The TurkStream, which runs along the bottom of the Black Sea from Russia's Anapa to Turkey, will consist of two lines, each with a capacity of 15.75 billion cubic meters of gas a year