PRAGUE — Czech police opened an investigation Tuesday into a “crime against the republic” following a Senate report that senior aides of the ailing president concealed that he was too ill to work, in the latest twist to a deepening constitutional crisis.

Hours later, Czech senators met with the new heads of Parliament’s political parties, who agreed to vote on whether to remove the president for being unfit to serve in office.

President Milos Zeman was hospitalized on Oct. 10, one day after populist Prime Minister Andrej Babis’s party appeared to have been ousted when opposition parties won a majority of seats in the Chamber of Deputies, the lower house of the Czech Parliament. The Czech president is tasked with appointing a prime minister to form a new government.

Police on Tuesday did not specify whom they intended to investigate, but attention turned to the president’s inner circle of advisers, who the Senate said had kept the public in the dark about the state of Zeman’s health.

Lawmakers and the media have accused Zeman’s chief of staff, Vratislav Mynar, of acting in the president’s name during the crucial post-electoral period, possibly even forging signatures on important state documents.

Babis, despite being a Zeman ally, singled out Mynar and demanded he resign, saying that “what he did is absolutely unacceptable.”

Zeman, 77, a lifelong smoker with a history of health problems, increasingly appeared in public in a wheelchair before this month’s vote. An admirer of Russian leader Vladimir Putin and China’s Xi Jinping, he had previously indicated he may ask Babis to form a government even if the prime minister’s party did not win a parliamentary majority.

Babis himself was already battling a public scandal after his use of shell companies to purchase a $22 million French chateau in 2009 was disclosed in the Pandora Papers, a massive trove of private financial records shared with The Washington Post and other media, shortly before the election.

But a state of political uncertainty soon turned into an unprecedented constitutional crisis after Zeman’s collapse raised questions about his ability to perform crucial post-election duties. The impasse was further exacerbated by Mynar’s refusal to provide any details about the president’s health and whether he was fit to work.

The president’s doctor then publicly spoke out on Oct. 14, alleging that Mynar brought the speaker of Parliament into Zeman’s hospital room to have the ailing president sign documents to reopen Parliament. The hospital said it had informed Mynar the day before that Zeman was too sick to work.

Police announced on Oct. 15 that they would open an investigation into whether the signature was forged.

The Czech public finally learned that Zeman was too sick to work on Monday, when the Senate, which is not controlled by Babis’s party, demanded and received a hospital report.

“Milos Zeman is currently unable to carry out any work duties for health reasons,” and his ability to return to office in the coming weeks is “very improbable,” Senate Chairman Milos Vystrcil said during a news conference Monday. He said Mynar had been aware of this prognosis since Oct. 13, according to the hospital.

Tuesday’s special parliamentary meeting concerned when and how to activate Article 66 of the Czech constitution, which allows presidents to be stripped of their powers if they are unable to perform their duties. To activate the article, a simple majority vote in both chambers of the Parliament is required.

“The report from the hospital was so clear that it’s not a question of whether the Senate will activate Article 66, but whether it will activate it unanimously,” said Michael Canov, a member of the Senate constitutional committee, during a news conference after the meeting Tuesday.

The Senate is expected to vote sooner than the lower chamber of Parliament, which will not meet until after its inaugural session on Nov. 8.

Once the article is activated, the president’s powers will be divided among the prime minister and the heads of the two parliamentary chambers.

The Czech police have not commented further on the details of their investigation.

“With regards to the new information, released by the Senate [on Monday], the police will launch investigation of possible unlawful acts, in which signs of crimes against the republic can be detected,” the Czech police tweeted Tuesday, according to a Reuters translation.

But some Czech officials already were taking action. Czech Foreign Minister Jakub Kulhanek on Tuesday tweeted that he had asked Martin Nejedly, another presidential adviser, to return his diplomatic passport within a week “or it will be revoked.”

Nejedly is among a number of staffers in Zeman’s office who have faced criticism for not having security clearances as the president’s office has forged close ties with Russia and China.

“Had the Senate not investigated, we would have still been in the dark today,” Sen. Miroslava Nemcova said Tuesday.

Berger reported from Washington.