The government of Gen. Augusto Pinochet banned the chief of the Roman Catholic Church's human rights mission from the country and raided the headquarters of two opposition political fronts today.

One day after the declaration of a national state of siege, authorities here confirmed that a decree had banned Ignacio Gutierrez, a Spanish-born Jesuit priest who heads the church's Vicariate of Solidarity, the leading human rights organization in Chile. Officials said he would not be allowed to reenter the country after a current trip to Europe.

Hours later, state security forces raided offices belonging to the Communist-backed Popular Democratic Movement and the center-left Socialist Bloc, arresting at least nine persons. Similar raids were reported in the industrial city of Concepcion, where the military banned all political meetings.

Police said 107 persons were arrested last night for violating a midnight-to-5 a.m. curfew imposed in Santiago after Pinochet announced the state of siege, which he said was needed to combat terrorism. Lawyers from the Vicariate of Solidarity filed court petitions today on behalf of seven persons who they said were taken from their homes by armed civilians believed to work for the secret police.

The government initiatives represented Pinochet's strongest offensive against opponents since the early years of his 11-year rule and prompted widespread speculation that the 68-year-old general had decided to abandon efforts at political liberalization for "the hard hand" he has often threatened during 18 months of political conflict.

Top government officials met at the presidential palace at midday to consider additional action under the first state of siege imposed since 1978, and the quiet but tense capital was swept tonight by reports of impending action against the media and political parties.

While opposition leaders weighed possible responses to the crackdown, the effective expulsion of Gutierrez provoked an immediate reaction from Archbishop Juan Francisco Fresno of Santiago, a conservative whose once cordial relations with the government have deteriorated sharply in recent months. A statement issued by Fresno's office called the measure "grave" and said the archbishop "cannot accept it."

"The harm that this decision causes to the image of the government will be the exclusive responsibility of those who made it," the statement added.

Foreign Minister Jaime del Valle told reporters that the decree against Gutierrez had been issued because of his remarks during a meeting of 12 Chilean bishops with about 200 political exiles in Rome last weekend. Gutierrez was reported as saying that a recent government list of 5,000 exiles prohibited from entering Chile "was done by extremely cruel people."

As vicar of Solidarity since December 1983, Gutierrez was in charge of a church organization that provides legal and occasional medical assistance to victims of human rights violations and that reports on incidents of killings, torture and other abuses by security forces. Created in 1976, the vicariate has clashed with the government frequently but authorities had never taken direct action against it.

The expulsion followed a sharp attack on the church Monday by Interior Minister Sergio Onofre Jarpa, who in announcing his resignation cited the bishops' meeting with exiles as evidence of a "climate" he said had defeated his efforts at political liberalization.

Yesterday, despite his dramatic announcement of "personal failure," Jarpa was reinstated in his post by Pinochet in a reversal that puzzled diplomats and politicians.

Right-wing government supporters, alarmed by Pinochet's new campaign, did not openly oppose the repressive measures but instead stressed what they said was a continuing government commitment to political transition. They were encouraged by Navy Commander Jose Merino, who declared that the official action "does not mean a hardening" of military rule.

Political associates of Jarpa maintained he had resigned in opposition to the government's new hard line and had rejoined the Cabinet only after receiving assurances that the political liberalization he has sought to implement since his appointment in August 1983 would be continued.

Other political observers pointed out that an all-out crackdown by Pinochet would involve considerable political risks. Much of the president's support is conditioned on continuing movement toward the democracy Pinochet has promised for 1989, these observers said.

However, Pinochet repeatedly has labeled the liberalization as a failure in recent weeks, and opposition politicians have interpreted the new measures as his attempt to rule exclusively by force.

"He has put the country in a very dangerous, explosive situation," said Genaro Arriagada, a Christian Democratic leader. "This is something that will strengthen the military on one side and the Communist Party on the other, while destroying the center. The government will either destroy itself or destroy the rational political alternatives."