The European Space Agency on Monday said it had to fire thrusters on one of its satellites to avoid a collision with a satellite from SpaceX's Starlink constellation.

"Experts in our #SpaceDebris team calculated the risk of collision between these two active satellites, determining the safest option for #Aeolus would be to increase its altitude and pass over the @SpaceX satellite," the agency tweeted via its ESA Operations account.

"The manoeuvre took place about 1/2 an orbit before the potential collision. Not long after the collision was expected, #Aeolus called home as usual to send back its science data – proving the manoeuvre was successful and a collision was indeed avoided."

SpaceX is an aerospace manufacturer and space transportation services company founded by entrepreneur Elon Musk.

SpaceX reportedly refused to move its satellite when alerted to the risk of collision, according to space journalist Jonathan O'Callaghan.

"SpaceX sent a short email to ESA saying they would not move their satellite," he tweeted. "It's not clear why – they didn't mention if the satellite was active or not, apparently (ESA weren't even aware what the satellite was)."

"ESA have been pretty frustrated with SpaceX so far. There has been very little communication regarding Starlink, despite repeated attempts by ESA to contact them (this is the first email SpaceX had sent)," he added.

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