Iran on Monday confirmed an explosion at one of its satellite launch pads, saying it was due to a technical fault, and criticized US President Donald Trump for "gleefully" tweeting about it.
Trump said the US had nothing to do with what he called a "catastrophic accident" at Semnan Space Centre in a tweet on Friday alongside a high-resolution picture pointing to apparent damage at the site.
Government spokesman Ali Rabiei said the launch pad had been vacant when last week's explosion occurred, in Iran's first admission that an accident occurred at the space center in the north of the country.
"The explosion was in the launch pad and a satellite had not yet been transferred there," Rabiei told state television.
"Fortunately, nobody was killed in this incident. It was a technical issue... and it's now clear how this happened."
Rabiei criticized Iran's foes for trying to "convey that they are capable of infiltrating our organizations for espionage and sabotage".
The spokesman also hit out at Trump over his tweet.
"We don't know why the US president would... post a satellite photo, kind of treating the subject gleefully," said Rabiei.
"Fortunately, our knowledge in this field is increasing by the day," he said referring to Iran's space program.
The incident comes after months of tensions between Tehran and Washington.
Trump last year unilaterally withdrew from a landmark 2015 international deal that placed limits on Iran's nuclear activities in exchange for the lifting of sanctions, and he reimposed crippling financial penalties.
"The United States of America was not involved in the catastrophic accident during final launch preparations for the Safir SLV Launch at Semnan Launch Site One in Iran," Trump said in the tweet.
Publicly available satellite photos showed plumes of black smoke rising from the space center on August 29.