FRANKFURT, West Germany (AP) _ The government on Thursday outlawed West Germany's most notorious neo-Nazi organization, and police discovered a small cache of weapons and Nazi propaganda in a search of the party headquarters.

During coordinated raids across the country, police confiscated knives, guns, ammunition, posters of Adolf Hitler and swastika-covered banners from members of the Nationale Sammlung.

''The Federal Republic is not about to become the roaming grounds for right-wing extremists,'' Interior Minister Friedrich Zimmermann said in announcing the ban.

The group's leader, neo-Nazi Michael Kuehnen, said he was considering legal action to fight the ban.

Founded last summer, the Nationale Sammlung had fielded candidates for next month's elections in Frankfurt and suburban Langen and said it hoped to run in other locations as well. Its platform included renaming a railway station after Hitler.

The ban forbids Nationale Sammlung members from carrying out any activities as a group, including fielding candidates for an election, and it bans them from using the name publicly.

It coincides with a growing concern in West Germany of a possible resurgence of ultra-rightist tendencies.

Late Thursday, the ZDF television network quoted Guenther Schleicher, head of the Hesse state Office for the Protection of the Constitution, as alleging that cases of murder and bank robberies have been linked to neo-Nazi parties in West Germany.

Schleicher also estimated about 2,000 neo-Nazis are in West Germany, although other officials have put the figure closer to 1,500.

''Germany, they're coming,'' Stern magazine said in a headline on this week's cover. Another headline sarcastically referred to the extremists as ''the nice Nazis from next door.''

A poll published Sunday by the Welt am Sonntag newspaper said another extreme right-wing group, the Republican Party, would win 11.5 percent of the vote nationwide if federal elections were held now.

The Republicans, headed by a former Nazi Waffen SS soldier, captured 7.5 percent of the vote in last month's elections in West Berlin. That sends 11 party members to the local legislature and gives the Republicans two seats in Parliament beginning next year.

Further to the right of the Republican Party are the neo-Nazis, who are split into about 10 different groups. The most notorious is Nationale Sammlung, which has about 170 members.

The interior ministry said Nationale Sammlung had expressed revolutionary and combative aims to change West German society. It also accused Kuehnen and his followers of building up neo-Nazi groups nationwide.

The organization supports expulsion from West Germany of foreign workers and asylum seekers.

Kuehnen has also been active with right-wing extremists from several countries in planning celebrations for the 100th anniversary of Hitler's birth April 20.

Contacted in Munich, Kuenhen said in an interview he would fight the ban in court. ''I see certain legal possibilities,'' said Kuehnen, who has served three prison terms for Nazi activities.

West Germany's ARD TV network showed police carrying knives, guns and a box filled with ammunition from Kuehnen's Frankfurt home, which serves as the party's headquarters. Kuehnen was not home during the raid.

The broadcast showed police in a workshop of the house, where Kuehnen and his supporters allegedly filed down bullets so they would cause more severe injuries.

Gottfried Milde, the interior minister of the state of Hesse, said most of the raids were in Hesse, which includes Frankfurt.

The other states where police staged raids included Bavaria and North Rhine-Westphalia, the federal interior ministry said.

Searches there turned up an air rifle, two steel helmets, a gas mask, three pistols for firing blanks, and Nazi propaganda.

Zimmermann said authorities were seizing any property they could find that belonged to the NS group, whose initials are identical to the best-known German abbreviation for Hitler's Nazi Party.

The Nazi Party has been banned since West Germany was founded in 1949.

Under West German law, the Interior Ministry may ban any organization it determines is spreading Nazi propaganda. Violations of the ban carry penalties of up to five years in prison.

There have been calls for the ministry to ban another neo-Nazi group, the Free German Workers' Party, which the interior ministry says has about 500 members. The party is under investigation in connection with arson attacks on foreign workers in West Germany.