Smithfield Foods Inc., extended the period when debt holders can receive a premium for agreeing to the pork producer''s offer to buy back $337 million in outstanding 7-percent senior unsecured notes due in 2011, according to the Associated Press. Smithfield said that holders of nearly $311 million in aggregate principal amount agreed to tender notes by Tuesday''s early tender date. Of that total, Smithfield Foods accepted for purchase nearly $264 million. Under the offer''s original terms announced Nov. 2, eligible debt holders who agreed to the offer by the early tender date are due to receive a total of $1,043.93 per $1,000 principal, including an early tender payment of $30. Under the amendment, debt holders who agree to the offer by its Dec. 1 expiration date also will be eligible for the $30 premium. Besides the extension of the tender premium period, other terms of the offer are unchanged.