North Korea sends condolences to Russia after St. Petersburg blast

April 5 (UPI) -- North Korea sent a letter of condolence to Russian President Vladimir Putin after the bomb blast in St. Petersburg.

According to Russian television network RT on Wednesday, the letter was from Kim Yong Nam, the president of the Presidium of the Supreme People's Assembly of North Korea.

It was not clear whether leader Kim Jong Un had a role in the statement.

"I express my deepest condolences to the president and the victims' families," Kim Yong Nam wrote, according to RT. "I hope the families will overcome their sadness as soon as possible."

North Korea and Russia have not stopped rebuilding ties that reflect their longstanding partnership that began before the 1950-53 Korean War.

The two countries recently signed a "labor immigration agreement" that would allow Russia to import more North Korean laborers.

Russia is one of the top destinations for North Korea forced laborers and tens of thousands of North Koreans now work in the country.

Moscow has also held the United States and South Korea partly accountable for the North's continued provocations, because the two countries continue to hold joint military drills.

The bomb blast in St. Petersburg on Monday killed 14 people and injured more than 50.

Akbarzhon Jalilov, a Kyrgyzstan-born man, has been identified as a suspect.

Russian authorities have arrested six people in St. Petersburg in connection to the case.

The suspects are all from Central Asia and may have recruited for the Islamic State, according to investigators, the BBC reported.