Zeman said in an interview with the Blesk broadcaster that proof for the accusations of Russian involvement in the poisoning of ex-Russian intelligence officer Sergei Skripal in the UK is insufficient.
"I want to know the facts. I will certainly welcome if the United Kingdom presents some evidence that the Russians wanted to kill agent Skripal," the president emphasized.
Zeman said that on Monday he instructed Czech intelligence to verify the accusations of the Russian side that the substance could be developed or stored in the Czech Republic.
"I do not believe this, but it is always better to have information from intelligence that this accusation is false, than to live in the belief that there can be something [truthful] in it," he said.
The president noted that he had not interfered in the process of the government's decision to expel three Russian diplomats. This step, he said, is not an effective tool in the "case of Skripal."
Zeman went on, saying that Moscow had not exerted pressure on him over the case of Sergei Skripal's poisoning.
"No one from Moscow contacted me [on the Skripal case] or has visited me. As for the expulsion of diplomats, I believe it is a bit excessive, but I do not mind. Let it happen. They will return after some time," the president said, commenting on statements by some Czech politicians about his pro-Russian stance.
The choice of which diplomats would be expelled from the Czech Republic was very thorough, Zeman added, noting that Prime Minister Andrej Babis and heads of security services were in charge of this work.
Earlier this week, over 25 countries, including the Czech Republic and other EU member states, as well as the United States, decided to expel Russian diplomats over Moscow's alleged involvement in the attack on Skripal and his daughter, which had been firmly denied by Russia.
London claims that Moscow had a role in the poisoning of the Skripals using A-234, a substance allegedly related to the Novichok class nerve agents developed in the Soviet Union. Russia has said it had destroyed its chemical weapons stockpile, which had been confirmed by the Organization for the Prohibition of Chemical Weapons (OPCW).
Moreover, Moscow suggested that some countries, including the Czech Republic, have been carrying out research on substances from the so-called Novichok project.
Zeman said that on Monday he had instructed Michal Koudelka, the head of the country's counter-intelligence service BIS, to check whether the Novichok-class nerve agent had been produced and stored in the Czech Republic. Koudelka said the response would follow within one month.