Protests delay start of German far-right party's key meet
Once the congress started the party's 600-odd delegates approved co-leader Alice Weidel as candidate for chancellor by acclamation ahead of a snap general election on February 23.
The two-day meet is also expected to agree the party's election programme.
The draft version of the manifesto includes a pledge to leave the euro, reversing Germany's exit from nuclear power and a tough immigration policy.
The programme was delayed by around two hours due to protests preventing delegates reaching the venue but eventually started just after 12pm (1100 GMT).
Police said at least 8,000 demonstrators had assembled outside the town's convention centre.
The protestors braved the cold to shout slogans such as "no to Nazis" and listened to music from a stage erected by organisers.
Late on Saturday morning, a police spokesman said there was "no serious unrest" but that one road on the way to Riesa remained blocked by protestors.
Protest organisers said earlier on Saturday that police had hit groups of demonstrators and deployed pepper spray.
A statement from protest organisers said more than 12,000 people had turned out from all over Germany to voice their opposition to the AfD.
"The congress was delayed by wide-ranging, colourful and determined protests in many locations inside and outside the town," the statement said.
Maria Schmidt, spokeswomen for the protest organisers, said: "Today we are protecting the right of people to live in safety without the fear of deportation or being attacked."
"We are all making it clear: Riesa is not a peaceful place for fascism," she said.
Stormy debates ahead
Inside the convention centre the congress got under way with condemnations of the protestors who had tried to prevent the meeting.
Weidel congratulated her party colleagues for "defying the left-wing mob" while her co-leader Tino Chrupalla accused the demonstrators of acting like "anti-democrats and terrorists".
Once the congress gets under way in earnest observers expect there to be stormy debates over some points of the party's programme.
One proposed amendment for example would commit the party to a policy of "remigration", meaning a wide-ranging campaign to expel foreigners from Germany.
Controversy has also been stirred by the party leadership's plans to replace its Junge Alternative ("Young Alternative") youth wing, which has been classified an extremist group by intelligence services.
Its members, mostly aged 16 to 30, have frequently been implicated in using racist chants and holding meetings with neo-Nazis.
The plan to replace the Junge Alternative is due to be discussed on Sunday but the leadership may struggle to convince enough delegates to achieve the necessary two-thirds majority needed.
The AfD congress comes days after Weidel was promoted by US tech billionaire Elon Musk in a livestream on his X social media platform.
The AfD is currently in second place in opinion polls, and has gone up slightly from 19 to 20 percent in recent poll averages.
The conservative CDU/CSU is leading at 31 percent while Chancellor Olaf Scholz's Social Democrats are fighting it out for third place with their Green coalition partners on 15 and 14 percent respectively.