VIENNA, Feb 12 (Reuters) - The magnitude of an "explosion-like event" in North Korea on Tuesday was roughly twice as large as that of a 2009 nuclear test in the country, an international nuclear test monitoring agency said.
"We can assume this is roughly twice as big in magnitude," Lassina Zerbo, director of the international data centre division of the Vienna-based Comprehensive Nuclear-Test Ban Treaty Organization (CTBTO) said.
North Korea said earlier it had carried out a third nuclear test on Tuesday.
The CTBTO's assessment was based on its measurement of a seismic event measuring 4.9 on the Richter scale, versus 4.5 in 2009. The U.S. Geological Survey said earlier that a seismic event measuring 5.1 had occurred. (Reporting by Michael Shields and Fredrik Dahl; writing by Georgina Prodhan)