The multi-billion dollar merger of mining giants Glencore and Xstrata is now not expected to be completed before the current deadline, the companies revealed on Friday.The long-stop date for the 'Glenstrata' tie-up, valued at $33bn, has already been pushed back two times as the firms await the approval of regulators in some of its markets, as well as the completion of an Xstrata court process as part of the transaction.Glencore said that it will give an update on the timing of the merger when it reports its full-year results on March 5th but "given the on-going regulatory process and the Xstrata court timetable, it will not now be possible to complete by March 15th 2013."The companies announced last month that the merger still remains conditional upon the receipt of the outstanding regulatory approval in China.The original deadline for the deal was the end of 2012.