Test launches of Russia's ill-fated Bulava ballistic missile will resume in August or September, a high ranking Russian Navy official said on Friday.

"In all, three test launches are to be carried out before the end of the year," he said.

A source close to the government commission probing the incident said earlier on Friday the failure of the Bulava's latest test launch, from the Dmitry Donskoy nuclear submarine in the White Sea on December 9, 2009, was caused by a defective engine nozzle.

Since then, all further Bulava test launches were put on hold pending the results of a government commission probe.

The source said it was not a design but manufacturing fault.

"It was simply that the missile wasn't built right," he said.

The Bulava (SS-NX-30), a three-stage liquid and solid-propellant submarine-launched ballistic missile (SLBM), has officially suffered seven failures in 12 tests. Some analysts suggest that in reality the number of failures was considerably larger, with Russian military expert Pavel Felgenhauer contending that of the Bulava's 12 test launches, only one was entirely successful.

The future development of the Bulava has been questioned by some lawmakers and defense industry officials, who have suggested that all efforts should be focused on the existing Sineva SLBM.

However, that would require major changes to the Borey-class submarines and the Russian military has insisted that there is no alternative to the Bulava and pledged to continue testing the missile until it is ready to be put into service with the Navy.

MOSCOW, July 23 (RIA Novosti)