The IRS said Friday it “lost” a trove of e-mails to and from the central figure in the agency’s targeting of Tea Party and other conservative groups leading up to the 2012 presidential election.

IRS officials told Congress it can’t get its hands on many of Lois Lerner’s e-mails prior to 2011 — because her computer crashed that summer, a claim that infuriated congressional investigators.

“The fact that I am just learning about this, over a year into the investigation, is completely unacceptable and now calls into question the credibility of the IRS’s response to congressional inquiries,” said Rep. Dave Camp (R-Mich.), chairman of the House Ways and Means Committee.

“There needs to be an immediate investigation and forensic ­audit by Department of Justice as well as the inspector general.”

Lerner headed up the IRS division that processed applications for tax-exempt status from conservative and other groups.

But the agency admitted last year that agents had improperly scrutinized conservative groups’ applications for tax-exempt status — a move that critics charge was a politically motivated plot to help re-elect President Obama.

Congressional investigators have shown that IRS officials in Washington closely monitored the handling of Tea Party applications, many of which languished for more than a year without action.

But so far, they have not publicly produced evidence that anyone outside the agency directed the targeting or even knew about it.

Lerner’s e-mails were important to the probe because they could show if anyone outside the IRS was involved.

Camp’s office said the missing ­e-mails are mainly ones to and from people outside the IRS, “such as the White House, Treasury, Department of Justice, FEC [Federal Election Commission] or Democrat offices.”

The IRS said its techies went to great lengths trying to recover data from Lerner’s computer in 2011 — but came up empty.

The agency was able to retrieve 24,000 Lerner e-mails from 2009 to 2011 because she forwarded those to other IRS employees. But an ­unknown number remain missing.

Sen. Orrin Hatch of Utah, the top Republican on the Senate Finance Committee, called Friday’s disclosure “an outrageous impediment” to the probe.