Police are looking into an email bomb threat targeting the Supreme Court and other locations but found no explosives so far, officials said Thursday, after a fifth such email was sent apparently from Japan.

The email, which was received just past midnight, claimed that "high-powered bombs with needles" had been planted at the Japanese Embassy, the Supreme Court and city halls across the country, and would go off from 3:34 p.m. Friday to 2:07 p.m. Saturday.

Police searched the locations but found no explosives so far.

The email was sent in the name of a Japanese law firm with the same address as the one used for the four previous bomb threats received in the country in recent weeks. The sender was listed as Takahiro Karasawa, an incumbent lawyer in Japan.

"This is wrong. I think my name is being misused without my permission. Some extremists are committing these crimes, as these types of offenses are sometimes not regulated in Japan," Karasawa wrote on X last Wednesday.

Police said they are taking steps to ask Japanese police for cooperation in the investigation through the Ministry of Justice, but no significant developments were made for over 10 days.

Such phishing scams involving sending emails by stealing the accounts of law firms or lawyers are prevalent in Japan, sources said. The Dai-Ichi Tokyo Bar Association also warned of such scams multiple times on its webpage.

A series of bomb threats via email in recent weeks targeting schools and government offices across the nation have sent police searching the area with special forces and sniffer dogs and people fleeing for safety.

On July 7, an email threatened to detonate a bomb at a library in the capital if opposition leader Lee Jae-myung of the Democratic Party was not killed by 3:34 p.m.

The Japanese police stepped up security on Monday after the South Korean Embassy in Tokyo received similar email threats vowing to blow up the embassy building. (Yonhap)