(Adds detail, foreign minister quote)

BERLIN, Jan 15 (Reuters) - Germany's domestic intelligence agency will investigate the anti-immigrant Alternative for Germany (AfD) to determine the extent to which the party has right-wing extremist motives, a Berlin newspaper reported on Tuesday.

Der Tagespiegel said that in a 450-page report, the BfV domestic intelligence agency had classified the AfD - Germany's main opposition party - as a "case to investigate". It said this would not, however, involve full-on surveillance of the AfD.

A BfV spokesman said he could not confirm the report but the agency would hold a news conference at 1400 GMT on the matter.

Germany's constitution contains strict safeguards against extremism, allowing for the close monitoring and even the outlawing of far-left or far-right parties.

Tagespiegel said that the BfV would peruse public statements made by AfD members and emerging links to the far-right Identitarian Movement, which says it wants to preserve Europe's identity and is being monitored by the BfV.

"Whoever discriminates against people on the basis of their origins is being racist and nationalist. Parts of the AfD are a case for the domestic intelligence office," Foreign Minister Heiko Maas tweeted, alluding to the report.

"But observing them won't solve the problems. Above all we need to deal with the AfD objectively and politically."

The German state of Thuringia said in September it would examine whether the regional chapter of the AfD was pursuing unconstitutional goals. This followed comments by Bjoern Hoecke, a state AfD leader, in which he decried Germany's main memorial to Holocaust victims as a "monument of shame".

At that time, the states of Lower Saxony and Bremen also said their own security services tasked with policing unconstitutional activity had placed the regional chapters of Young Alternative, the AfD's youth wing, under surveillance because of suspected ties to extremists. (Reporting by Michelle Martin Editing by Mark Heinrich)

Our Standards: The Thomson Reuters Trust Principles.