New Delhi, July 20 (IANS): India's elite investigating agency, the Central Bureau of Investigation (CBI) is facing a shortage of one-fourth of officers, a senior official said here Monday.

"There are 1,451 posts sanctioned for the investigating officers - who are of the rank of sub-inspectors and additional superintendents. Out of this, 376 posts are lying vacant," CBI's Additional Director S.C. Sinha said while briefing reporters about the overview of the agency.

Sinha said there was a plan to fill the vacancy by recruiting people from the central paramilitary forces. "We are now not getting people from the central paramilitary forces as these forces are themselves struggling with the shortage of men."

He said there could be 10-15 percent vacancy positions in all ranks. "I am not sure about this figure, but what I estimate is that there could be 10-15 percent positions vacant at all ranks in the agency."

The CBI has a total strength of 5,886 personnel of all ranks.

Sinha said the agency registered 991 cases in 2008 out of which charge sheets were filed in 843 cases. Trial was concluded in 642 cases and conviction rate was 66.2 percent.

Asked why the conviction rate has gone down in the past few years, Sinha said: "We have been examining the issue very closely and identified three prime reasons for this.

"First, in some cases, court took adverse view and did not appreciate the evidence gathered by us. In some cases, there were flaws in the investigation and some cases saw weak prosecution.

"We are making all efforts to ensure improved quality of investigation and also ensure that the cases are properly taken up in the courts," Sinha said.

CBI Director Ashwini Kumar said he was hopeful that the investigation of every new case would be completed within one year.