Updates with inauguration, remarks in paragraphs 3-4, 10, 12

By Alvaro Murillo

SAN JOSE, May 8 (Reuters) - Costa Rica's Laura Fernandez took the oath of office as president on Friday, with the right-wing politician vowing to wage a war on crime in the small Central American nation, long recognized as a bastion of peace and prosperity.

Fernandez, 39, promised sweeping reforms to the judiciary and existing security laws to bolster security.

"Costa Rica cannot normalize the shame of seeing its institutions penetrated by crime. We cannot see that the drug traffickers find cracks in our system," Fernandez said in her inaugural address.

"The reform we need is profound and we are going to promote it without fear," she said.

Last week, Fernandez introduced Gerald Campos as her new security minister, vowing "a heavy-handed war against organized crime."

Costa Rica, which abolished its military in 1948, has long been famed as one of the region's most peaceful nations even as its neighbors endured violent dictatorships, military interventions and civil wars.

However, its murder rates broke records during the four-year term of Fernandez's predecessor Rodrigo Chaves, which the U.S. attributed to Costa Rica becoming a key transit point for South American cocaine shipments destined for the U.S. and Europe.

Fernandez served as presidency minister under Chaves, who will continue to play an important role in the nation's politics as leader of her Sovereign People party and as Fernandez's own presidency and justice minister.

Chaves, who could not stand for re-election under Costa Rican law, had during his term repeatedly criticized the judiciary, prompting critics to accuse him of authoritarian tendencies reminiscent of nearby El Salvador's President Nayib Bukele.

Fernandez on Friday said she would soon inaugurate a maximum security prison that Costa Rica is building and which is modeled after El Salvador's anti-terrorism CECOT center, where hundreds of Venezuelans were held without trial after being deported from the U.S. early last year.

Human rights groups have said detainees at El Salvador's prison - many of whom were sentenced in mass trials - have been subjected to torture, and deprived of food, medical care and legal services.

Fernandez also promised that Costa Rica would soon have "one of the most modern police surveillance centers in the world."

Fernandez, who will serve until 2030, won the February election with 49% of the vote and 31 of 57 seats in the country's single-chamber legislature, providing the ruling party with an absolute majority.

Fernandez was sworn in on a Bible and the Costa Rican constitution at the capital's National Stadium, whose construction was a 2007 gift from China, though her predecessor Chaves distanced himself from the Asian powerhouse during his term as he positioned himself closer to Washington.

Spain's King Felipe VI, Israeli President Isaac Herzog and U.S. Deputy Secretary of State Christopher Landau were set to attend, as well as the presidents of nearby Panama, Guatemala and the Dominican Republic. Bukele, however, missed the event, as did neighboring Nicaragua's President Daniel Ortega.

Despite record murder rates, Chaves' presidency was marked by a strong post-pandemic economic recovery, low inflation and a reduction in poverty, though job creation remained limited.

Fernandez takes over the nation of just over 5 million people at a time of geopolitical uncertainty marked by the U.S.-Israeli war on Iran that has sent oil prices rocketing worldwide, and potentially greater fiscal pressures.