Altmaier “tripped and fell as he left the stage,” the spokeswoman said. “He was treated by doctors on the scene and brought to hospital for tests.”
She said the close ally of Chancellor Angela Merkel was speaking and had thanked the doctors and medics who treated him.
DPA reported that the 61-year-old veteran of Merkel's Christian Democratic Union (CDU) party had suffered a broken nose, bruises and light head wound.
TV footage showed Altmaier stepping down from the podium at the Digital Summit in Dortmund, western Germany, and then cut to the audience applauding, before they gasped at the sight of his fall.
North Rhine-Westphalia's premier Armin Laschet (CDU), who had given a speech before Altmaier, said: “We were all holding our breath. It's a good thing that a doctor and professor of medicine was with him immediately.”
A screen was set up to shield the first aid operation from view in the hall where Altmaier had just given a speech, while audience members were asked to leave.
A screen was set up to shield Altmaier. Photo: DPA
An AFP photographer then saw him being transported to hospital in an ambulance.
Politicians took to social media to wish Altmaier well.
CDU leader Annegret Kramp-Karrenbauer wrote on Twitter: “What a shock! Dear Peter Altmaier, I wish you a speedy recovery and that you can get back on your feet quickly.”
Was für ein Schreck! Lieber Peter Altmaier, ich wünsche Dir gute Besserung und dass Du schnell wieder auf die Beine kommst.
— A. Kramp-Karrenbauer (@akk) October 29, 2019
Vice Chancellor and Finance Minister Olaf Scholz, of the Social Democrats, also wished him a quick recovery and added: “Hopefully we'll see you again in the cabinet very soon.”
— Olaf Scholz (@OlafScholz) October 29, 2019
According to cabinet rules, Scholz would represent Altmaier should he be absent for a longer period of time.
Chancellor Merkel's spokesman also wished Altmaier a speedy recovery on behalf of the federal government.