BlackBerry Ltd, which recently concluded a $1 billion convertible debt offering, said it has agreed with its debtholders to extend an option deadline attached to the deal, giving potential investors a chance to buy up to a further $250 million in convertible debt.

The struggling smartphone maker last month shelved plans to sell itself and instead opted to raise funds via a $1 billion notes offering led by Fairfax Financial Holdings <FFH.TO>, its largest shareholder.

In a brief statement late on Thursday, BlackBerry said the earlier announced investor option to purchase up to an additional $250 million of convertible debentures, as part of the offering, has now been extended to January 13, 2014.