Islamic militants disguised themselves as street cleaners to carry out two bomb blasts last month in Atyrau, the capital of Kazakhstan's biggest oil- producing region, the Prosecutor General's Office said.


The explosions near buildings housing local prosecutors and the city's mayor were part of "an action plan to frighten law- enforcement and other state officials," the Astana-based office said in a statement on its website today. The attackers dressed in the uniform of communal-service employees while planting the bombs, according to the statement.


Prosecutors confirmed that an armed offshoot of the Jund al-Khilafah group trained the four men behind the blasts. One of them died when a bomb he was carrying exploded prematurely.


Kazakhstan, a predominantly Muslim former Soviet republic that borders Russia and China, has seen an upsurge of attacks in its oil-rich regions. The authorities detained 18 suspects and killed one for resisting arrest Aug. 29.


Ten Muslim militants in the Aktobe region were shot dead after killing a member of a police special-forces unit, the Vremya newspaper reported July 14. Three policemen were killed in a separate July attack in the region, the newspaper said.


TengizChevroil LLP, the Kazakh oil venture led by Chevron Corp. (CVX) and the nation's biggest oil exporter, produces crude in the Atyrau region near the Caspian Sea.