BERLIN - Two German states said on Monday they have begun surveillance of youth wings of the far-right Alternative for Germany (AfD) as calls grew for a broader monitoring of the biggest opposition party and its ties to the anti-Islam PEGIDA group.About 6,000 supporters of the two groups demonstrated in the eastern city of Chemnitz on Saturday against the fatal stabbing of a man, allegedly by two migrants.Last week skinheads clashed with police soon after a Syrian and an Iraqi were identified as the main suspects, and a number of xenophobic attacks were reported, exposing bitter divisions over Chancellor Angela Merkel's liberal immigration policy.Security officials in Bremen began monitoring the Junge Alternative group last week, Rose Gerdts-Schiffler, a spokeswoman for the city-state's intelligence service said.Neighboring Lower Saxony will also observe the local AfD youth group, with the state's interior minister Boris Pistorius citing "unmistakeable signs of structural ties to organized right-wing extremists."Surveillance is a sensitive issue in Germany after the abuses by the Gestapo during the Nazi era and the Stasi in Communist East Germany during the Cold War.However, an opinion poll by the Civey Institut for Funke Mediengruppe on Monday found that 57 percent of Germans agreed that the AfD - which has 92 seats in the 709 seat lower house of the federal parliament - should be monitored by the government.One top AfD leader Joerg Meuthen told supporters on Monday there had been no violence against non-Germans in Chemnitz and his party should not be put under surveillance. He faulted Merkel for "fake news" and said she should step down.Another AfD leader, Alexander Gauland, has described public anger after the stabbing in Chemnitz as justified, but insisted his party does not support extremism.Intelligence agencies already monitor members of Germany's far-left and far-right as well as Islamists suspected of planning attacks.Andrea Nahles, who leads the junior coalition Social Democrat party, backed surveillance of the AfD as a whole. "After Chemnitz, there are good reasons to do that. The AfD allowed itself to become a front organization for radical rightists on the streets of Chemnitz, either willingly or unwillingly," she said.Federal Interior Minister Horst Seehofer and his Bavarian CSU party believe the conditions have not been met to monitor the AfD as a whole, but say they will keep an eye on developments and individuals.AFD SUPPORT RISINGBavarian premier Markus Soeder, whose conservative CSU faces big losses to the AfD in an October state election, questioned whether there were sufficient grounds to warrant observation of the entire party.Still, he told the broadcaster ntv that individuals could possibly be monitored. "It's not just about an opposition party; they have a hidden agenda," he said. "We have to send a clear signal in Bavaria that we don't want what happened in Chemnitz."Support for the AfD, which won nearly 13 percent in last year's federal election, rose two percentage points to 16 percent in an RTL opinion poll after the events in Chemnitz.Critics have faulted the party for not expelling Bjoern Hoecke, an AfD leader from the state of Thuringia who has criticized a memorial to victims of the Nazi Holocaust as a "monument of shame" and helped organize Saturday's march.Authorities in Saxony, where Chemnitz lies, were more cautious. Martin Doering, spokesman for the state's intelligence service said it was too soon to discuss surveillance of the party there and investigations into possible right- and left-wing extremism surrounding the Chemnitz case might take weeks.