The Spanish police, always diligent in the pursuit of what they considered leftist enemies of the state, are for the first time in 48 years going after rightist extremist groups that once were allies and "Ideological collaborators" of the late dictator Francisco Franco's law enforcement agencies.

The chase is reluctant, and Spanish authorities have yet to charge any Spaniard with an act of violence against leftists. Nevertheless, the detention last week of 14 rightists, two of them Spaniards, has eclipsed in the minds of the Spanish public the continuing arrests of leftist extremists and Communists throughout the country in the past month.

The crackdown on rightist extremists coincided last week with the beginning of Supreme Court deliberations on the Spanish Communist Party's bid for legalization. The party has been outlawed since 1939, when Franco's forces defeated the short-lived Spanish Republic.

The pursuit of rightists followed threats against the life of Premier Adolfo Suarez, architect of Spain's democratic reforms and the leader who ordered tolerance of Communists until the court rules whether the party is legal and thus able to enter candidates in the parliamentary elections scheduled for this Spring.

The threats Suarez were reportedly made by the Apostolic Anti-Communist Alliance, a secretive fascist terrorist group.

Police have detained a rightist Argentine, Jorge Cezarsky, in connection with the killing of a student in Madrid last month.

Last week authorities arrested Mariano Sanchez Covisa, 58, believed to be the head of the Warriors of Christ, a rightist terrorist organization.

Another Spaniard, 10 Italians wanted in their country for rightist violence and a Frenchwoman were also arrested. Police said the arrests were connected with an arms-making plot.

Sanchez Covisa, who defends violence as "necessary" because the government is following "foreign orders," and three of the Italians were jailed Friday under Franco's harsh anti-terrorism law, which the government revived last month. Ironically, the law was created by the late dictator to punish Basque separatists and Communist guerrillas.

The murders of at least seven leftists, apparently by rightist terrorists, remain unsolved. Two were killed in Navarre in May and five Communists were slain in Madrid in January.

In contrast to the small number of rightists detained, hundreds of leftist extremists have been arrested in the past month. The arrests came in connection with police attempts to solve the kidnaping of Antonio Maria deOriol y Urquijo, 63, president of the Council of State, and Lt. Gen. Emilio Villaescusa, 64, president of the Supreme Military Tribunal. The two had been held by the Oct. 1. Anti-Fascist Resistance Group, known as GRAPO.

The question now is whether police will strive to be as zealous in solving rightist terrorist actions as they are in pursuing leftist extremists.

"The transition to a democracy can't work until the right loses its immunity and police protection," observed a diplomat here. "The police know how to deal with left-wing terrorists. But when it comes to the right the Civil War Victor complex takes over."

"There is no question about it," said a Spanish official. "Police drag their feet when dealing with right extremist." Trained by Franco to fight Communist and leftist "subversives," political police welcomed the "help" of "rightist ideological collaborators" like the Warriors of Christ, the official said.

The Warriors of Christ took the blame for "things police wanted to do but could not get away with," the official added. This included buring leftist bookstores and art galleries, beating up "leaftist demonstrators," and raiding university classrooms to "thrash subversive students" with bicycle chains.

Last week several members of Warriors of Christ arrested for an attack at Madrid University were released.

The relationship between the police and rightist gangs dates back to the end of the Civil War, when trusted citizens "reported" on the activities of suspected Communists, Masons and sympathizers of the Republic.

"The system became fixed, a part of our police system," the official went on. "Now it must be ended. In a democracy police must protect all Spaniards, not just those who are politically safe."

This, of course, is a problem that King Juan Carlos and Suarez must solve before the parliamentary election campaign starts in the weeks ahead.

In addition to the Warriors of Christ and the Apostolic Anti-Communist Alliance there are at least 16 openly fascist and Nazi organizations. They are anti-Semitic, anti-United States, anti-Soviet, anti-Communist, anti-Masonic, anti-capitalist and oppose Spain's liberal church hierarchy. Several are legal and have their own slick publications to propagate their line. Subscribers include police and military officers.

In its efforts to deal with extremists of the right and left, the Spanish government has an ally of sorts in the Communist party.

The party, whose leaders want to use legalization and the ballot as a way to power and participation in Spain's dawning democracy, have condemned GRAPO and other leftist terrorist violence "because it gives [the government] anexcuse to slow down the liberalization process."