"She was detained after the prosecutor general read out her indictment," the prosecutor's spokesman Andriy Lysenko told AFP by phone hours after lawmakers voted to lift Savchenko's immunity from prosecution.
Savchenko had planned "a large-scale terrorist act in the centre of the Ukrainian capital," general prosecutor Yuriy Lutsenko told lawmakers in parliament earlier.
He claimed she had made a deal with leaders of Russian-backed separatist republics in the country's east to "obtain the weapons necessary for such an attack, in particular mortars of 120 mm caliber, small arms, sniper rifles, combat grenades".
Lutsenko said the planned attack would have brought a "sea of blood, chaos" to central Kiev.
He showed lawmakers a 30-minute video of a woman who looked like Savchenko talking to two apparently Ukrainian officers about plans to attack parliament.
"I propose a coup d'etat, they should be eliminated physically, all of them in one moment," said a woman resembling Savchenko in the video, before drawing a plan of parliament to explain where to throw grenades inside the building to create an explosion.
"Just one person can do it in a minute and a half...I myself will certainly be able to throw six grenades," the woman in the video said.
Savchenko was present in the chamber during the video broadcast and watched it with a smile, but did not provide any explanation.
The parliament approved lifting Savchenko's immunity from prosecution as an MP and, in a separate vote, authorised her arrest by 268 votes to 10, minutes after Lutsenko's speech.
In 2014, the 36-year-old former combat pilot was captured while fighting against Kremlin-backed separatists in eastern Ukraine and found guilty of involvement in the killing of two Russian journalists in the country's war-torn east.
She spent around two years in a Russian prison and became a symbol of Ukraine's resistance, launching several hunger strikes.
Savchenko returned to a hero's welcome to Kiev in May, 2016 as part of a prisoner swap with Russia.
But her political star has faded since her return to Kiev, where she became a lawmaker for former prime minister Yulia Tymoshenko's political party.
She has regularly stirred controversy and contradicted President Petro Poroshenko's policies by supporting direct talks with pro-Kremlin separatists and visiting rebel-held territory.
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