Slovak Prime Minister Robert Fico's condition has stabilized overnight but is still "very serious", the deputy prime minister said on Thursday, a day after Fico was shot multiple times.

"During the night doctors managed to stabilise the patient's condition," said Robert Kalinak, who is also the Defense Minister, adding, "Unfortunately the condition is still very serious as the injuries are complicated."

Tomas Taraba, another deputy, told the BBC he believed Fico's hospital procedure had gone well.

"I guess in the end he will survive," Taraba said. "He's not in a life-threatening situation at this moment."

Earlier, Interior Minister Matus Sutaj Estok told reporters at a hospital in the central city of Banska Bystrica that the 59-year-old leader was "in critical condition and his life is in danger."

Police detained a suspect at the site of the attack in Handlova, President Zuzana Caputova told reporters.

"I am shocked, we are all shocked by the terrible and heinous attack," she added.

Kalinak would not give information on the suspect but described the attack as "a political assault."

"It's absolutely clear, and we have to react on that," he stressed.

Fico was shot multiple times, according to a post on his official Facebook page.

"Today, after the government meeting in Handlova, there was an assassination attempt on Fico," the government said.

Media reported that the suspected gunman was a 71-year-old writer, with Interior Minister Matus Sutaj Estok confirming the reports.

"I think I can confirm this, yes," the minister told reporters when asked about reports identifying the man detained at the scene of the shooting in the town of Handlova.

A grey-haired suspect was seen being handcuffed on the ground just after Fico was shot several times after a government meeting.

Media reports said the suspect was a founder of the DUHA (Rainbow) Literary Club and was from the town of Levice.

The reports, which also named him, said he has written three poetry collections and is a member of the official Association of Slovak Writers.

The association confirmed on Facebook that the man had been a member since 2015, adding that if his identity as the suspected shooter was confirmed, "the membership of this despicable person will be immediately canceled."

In addition to his current stint as premier, Fico headed the government in 2006-10 and 2012-18. Since returning to office last October, Fico has made a string of remarks that have soured ties between Slovakia and neighboring Ukraine. After he was elected, Slovakia stopped sending weapons to Ukraine. He had already pledged during the electoral campaign not to provide Kiev with "a single bullet."

Read more: ‘No air defense, no air force’: Slovakia says after Ukraine aid