Commission Regulation (EC) No 2734/2000 of 14 December 2000 amending Regulation (EEC) No 1627/89 on the buying-in of beef by invitation to tender and derogating from or amending Regulation (EC) No 562/2000 laying down detailed rules for the application of Council Regulation (EC) No 1254/1999 as regards the buying-in of beef