We report tectonomagnetic results from the epicentral area of the 27 September 2003 Ms=7.5 earthquake in the Altay mountains, southern West Siberia. The results were obtained in the first three survey campaigns in early October 2003, late November 2003, and latest May-early June 2004 using an array of one continuous-measurement station and fifteen repeated-survey sites. Changes in total geomagnetic field associated with seismic activity were mostly of regional scale and usually did not exceed 1.5 nT. The M=4.5 aftershock of 31 May 2004 was accompanied by an anomaly of 1-2 nT. The location of the anomaly within highly magnetic rocks can be evidence of its piezomagnetic origin.