Iran has released Russian journalist Yulia Yuzik after detaining her for a week, according to the Russian Embassy in Tehran.

The reason for Yuzik's arrest in Tehran remains unclear.

"As a result of joint efforts by the Russian Foreign Ministry and the Russian Embassy in Tehran, the Iranian side resolved to release Russian citizen Yulia Yuzik," the embassy said in a statement on October 10.

Yuzik "flew to Moscow from Tehran on board an Aeroflot flight" early in the day, the statement added, while the embassy's press attache, Andrei Ganenko, said the investigative journalist "feels well."

Her ex-husband, journalist Boris Voitsekhovsky, said on social media she had landed in the Russian capital.

Yuzik returned to Tehran on a private visit on September 29 after working as a freelancer for several years in Iran.

Iranian officials seized Yuzik's passport upon arrival at the Imam Khomeini International Airport, and she was arrested at her hotel room on October 2, the Russian Embassy has said.

An Iranian government spokesman said Yuzik was being held over alleged visa violations, but Voitsekhovsky has claimed she was suspected of having ties to Israeli intelligence services.

Earlier this week, Reporters Without Borders (RSF) called on the Iranian authorities to immediately release Yuzik, saying that "visa issues could not constitute grounds" for detaining her.

Previously, the 38-year-old Yuzik had worked for the Rostov bureau of the Komsomolskaya pravda newspaper and the Russian edition of Newsweek magazine.

She embarked on a writing career in 2003 while engaging in investigative journalism projects.

Based on reporting by RIA Novosti, TASS, and the BBC