BERLIN - Pressure grew on Germany's domestic spy chief on Saturday after he expressed skepticism that migrants had been hounded in Chemnitz after the fatal stabbing of a German man - remarks that are reviving strains in Chancellor Angela Merkel's government.Germany has been deeply shaken by the most violent right-wing protests in decades after the Aug. 26 killing of the German man in Chemnitz, in the eastern state of Saxony, for which two immigrants were arrested. Friday's comments by Hans-Georg Maassen, head of the BfV domestic intelligence agency, aggravated tensions about whether politicians and the authorities are being too complacent in the face of rising xenophobia in Germany, where many thought the lessons of its Nazi history had long been learned.Maassen said he was skeptical about "media reports on right-wing extremists hunting down people in Chemnitz", adding that a video circulating showing that happening could have been faked.The mass-selling daily Bild, in its Saturday edition, called Maassen's remark "the most explosive quote of the year".His comments undermined Merkel, who had said pictures had shown "hate and ... the persecution of innocent people".After a batch of opposition politicians called on Friday for Maassen to go, members of the ruling parties - Merkel's conservatives and the left-leaning Social Democrats (SPD) - raised doubts about him on Saturday.Stephan Weil, SPD premier of the state of Lower Saxony, questioned whether Maassen was still up to his job. "For me, the question marks are growing," Weil told the Funke media group.Patrick Sensburg, a lawmaker with Merkel's Christian Democrats (CDU), said Maassen would have to explain himself to a parliamentary committee that oversees Germany's spy agencies, which meets behind closed doors on Wednesday."President Maassen will now have to explain how he came to his assessment and why he made it known via the media," Sensburg told the Handesblatt business daily.The row over whether or not migrants were hounded in Chemnitz has inflamed tensions over immigration in Merkel's 'grand coalition' only two months after she reached a truce with her Bavarian sister party on the same issue.Interior Minister Horst Seehofer, of the Bavarian Christian Social Union (CSU), said on Friday he had no reason to doubt Maassen's assessment. On Wednesday, Seehofer said: "Migration is the mother of all problems."Merkel's spokesman, asked on Friday about her trust in Maassen, said: "Mr Maassen has an important and responsible role."Merkel on Thursday accused the far-right Alternative for Germany (AfD) party of using violent protests over the Chemnitz stabbing to stir up ethnic tension.