A woman, believed to be the mother of two children whose remains were found in suitcases in New Zealand last month, is transported to prosecutors' office, in Ulsan, South Korea, September 15, 2022. YONHAP NEWS AGENCY / REUTERS

A woman was arrested in South Korea on Thursday on two murder charges from New Zealand, where the bodies of two long-dead children were found last month in abandoned suitcases, authorities said.

Authorities didn't immediately say if the 42-year-old suspect was the dead children's mother. New Zealand police had earlier told their South Korean counterparts that the mother might be living in South Korea.

South Korean police detained the woman in the southeastern port city of Ulsan, based on a South Korean court warrant issued after New Zealand requested her provisional arrest as part of an extradition process, according to South Korea's National Police Agency and Justice Ministry.

"Police arrested the suspect at an apartment in Ulsan on Thursday following a stakeout with tips on her whereabouts and CCTV footage," South Korea's National Police Agency said in a statement.

"The suspect is accused by the New Zealand police of having murdered her two children -- aged seven and 10 at the time -- in around 2018 in the Auckland area."

"She's been found to have arrived in South Korea after the crime and has been in hiding ever since," it added.

The unidentified woman covered her face with the hood of her coat as officers escorted her outside an Ulsan police station and put her in a car headed for the capital, Seoul, where she was expected to be questioned by prosecutors.

The woman, who was wearing ripped jeans and sandals, was asked by local media whether she would confess to the killings.

"I didn't do it," the woman said repeatedly, as she was led away and put into a police vehicle.

New Zealand authorities must submit the formal request for her extradition to the South Korean Justice Ministry within 45 days. The ministry will then decide whether to proceed with an extradition review at the Seoul High Court to rule whether she would be sent to New Zealand.

New Zealand police said the South Korean warrant was in connection with two charges of murder, and they have asked South Korean authorities to keep the woman in jail until she is extradited.

"To have someone in custody overseas within such a short period of time has all been down to the assistance of the Korean authorities and the coordination by our New Zealand Police Interpol staff," Detective Inspector Tofilau Fa'amanuia Vaaelua said in a statement.

He said the investigation had been "very challenging" and that inquiries were continuing both in New Zealand and abroad.

Vaaelua said police weren't going to comment further as the matter was now before the courts. Authorities in New Zealand typically don't comment on pending court cases in order to avoid the possibility of influencing the outcome.

The children's bodies were discovered last month after a New Zealand family bought abandoned goods, including two suitcases, from a storage unit in Auckland in an online auction. Police said the New Zealand family had nothing to do with the deaths.

The children were between 5 and 10 years old, had been dead for a number of years, and the suitcases had been in storage for at least three or four years, according to police.

South Korean police say the woman was born in South Korea and later moved to New Zealand, where she gained citizenship. She returned to South Korea in 2018, according to immigration records.

South Korean police say it was suspected she could be the mother of the two victims, as her past address in New Zealand was registered to the storage unit where the suitcases were kept for years.