The president of the Czech Republic Milos Zeman said on Sunday (April 25) the idea that Russian spies caused a 2014 ammunition dump explosion in the country was just one of two theories.
His statement comes just over a week after the government sparked a row with Moscow over the case - which caused the worst dispute between the two countries in decades.
The Czech government said it suspected that two Russian spies -- accused of a nerve agent poisoning in Britain in 2018 -- were also behind the Czech 2014 explosion that killed two people.
Moscow has denied any role in either event.
On April 17, Czech Prime Minister Andrej Babis said that there was well-grounded suspicion of the involvement of a Russian military intelligence service in the explosions.
Zeman, the head of state who appoints prime ministers but is not involved in the day-to-day running of the country, has often taken pro-Russian views.
The Czech government expelled 18 Russian diplomats and other embassy staff it identified as spies last week, which Zeman said he supported.
It ordered a further 63 diplomats and Russian staff to leave by the end of May, to bring the Prague Russian embassy to the same level as its Czech counterpart in Moscow.
Moscow retaliated by ordering out 20 Czech diplomats and staff.
The European Union and NATO have issued statements in support of the central European country and the Baltic states and Slovakia have expelled Russian diplomats in solidarity.