By Jan Lopatka
PRAGUE (Reuters) -Czech President Milos Zeman said on Sunday the idea that Russian spies caused a 2014 ammunition dump explosion in the central European country was just one of two theories and the possibility it was an accident should not be ruled out.
Zeman's statement came just over a week after the government sparked a row with Moscow by saying 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.
In his first public remarks on the case, Zeman said in a pre-recorded speech there were two theories.
"We are working with two investigative theories - the first, original one, that there was an explosion resulting from inexpert handling of explosives, and the second that it was an operation of a foreign intelligence service," he said in the speech, carried on Prima television.
"I take both of these theories seriously and I wish for them to be thoroughly investigated," he said.
Prime Minister Andrej Babis said on April 17 that there was well-grounded suspicion of the involvement of Russian military intelligence service GRU in the explosions. The government has not announced any other possible version of the events.
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. He has argued for the purchase of Russian Sputnik V vaccines and for inviting Russia's Rosatom to take part in a tender to build a nuclear power station.
Zeman said Rosatom should be excluded from the tender if Russia's involvement in the explosion is proven. The government has already said it would not include the company.
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.
The expulsions greatly reduce what has for decades been the biggest foreign mission to Prague, which Czech counterintelligence service say was a hub for spying activities.
Moscow retaliated by ordering out 20 Czech diplomats and staff, and also requiring the Czechs to cut by May about 90 Russian support staff working at the Czech embassy and a complex including a hotel for Czech visitors to Moscow.
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.
Zeman said that there was no evidence the two spies entered the Vrbetice facility, a complex of warehouses 330 km (205 miles) east of Prague, but added it was also not excluded they did and the suspicion of their involvement was serious.
Pavel Fischer, head of the foreign, defence and security committee of the upper house of parliament and a member of the opposition, said he had been shown confidential information that was sufficiently conclusive and that Zeman's doubts were damaging the country in the eyes of its allies.
"Zeman now openly stands on the side of Russia and has become its advocate," Fischer said in a Facebook post.
(Reporting by Jan Lopatka, additional reporting by Michael Kahn; editing by Philippa Fletcher)