Apple is cooperating with U.S. government inquiries into its secret slowdown of older iPhones, further complicating its efforts to move past an issue that irked customers whose devices bogged down.

The company acknowledged the probes after both The Wall Street Journal and Bloomberg had reported the U.S. Justice Department and Securities and Exchange Commission were investigating how investors have been affected by Apple's handling of the situation.

A software update released in 2016 began to slow down older iPhones when their batteries weakened to prevent them from abruptly turning off, but Apple didn't fully disclose what it was doing until December.

Apple has since apologized for not being more forthcoming and is replacing batteries on older iPhones for $29, a $50 discount.