MOSCOW. Aug 27 (Interfax-AVN) - Traces of explosives were discovered during examination of fragments of a Siberia Airlines TU-154 Careless airliner that crashed on Tuesday, Federal Security Service (FSB) spokesman Sergei Ignatchenko told Interfax on Friday.
"A study of the fragments of the TU-154 aircraft discovered traces of an explosive substance. A tentative analysis indicated that it was cyclonite," Ignatchenko told Interfax on Friday.
Additional examinations are under way, he said.
The FSB is continuing to probe the Tuesday night crashes of airliners in the Tula and Rostov regions together with the prosecutor's office and the Interior Ministry.
FSB specialists on explosives and technical experts are working at the scene, Ignatchenko said.
"Information has been collected in the process of operational and search efforts to help to determine the circle of people who may have been involved in an act of terrorism aboard the TU-154," Ignatchenko said.
Examination of the fragments of the other aircraft, a Volga- Aviaexpress TU-134 Crusty, is continuing, he said.
"No new data has been collected yet," he said.