Vettel, in his last few races for Ferrari before joining Aston Martin (Racing Point) next season, was fifth fastest.
"It’s like driving on grass - way lower grip than a wet track," commented Haas's Kevin Magnussen.
Mercedes' Lewis Hamilton, who looks set to seal his record-equalling seventh world championship in Sunday's race, was only 15th fastest and more than five seconds slower than Verstappen.
"There's no grip, it's pointless doing the start," the Briton said over the team radio when told to pit for practice starts.
Team mate Valtteri Bottas, who must score eight points more than Hamilton to stay mathematically in contention, was ninth fastest with the main priority being to get rubber down onto the track.
"It's all about tyre temperature," said Red Bull boss Christian Horner, whose team finished one-two in 2011.
"It's so, so slippery out there it is like driving on ice in many respects."
McLaren's Carlos Sainz stopped by the side of the track after earlier suffering an electrical problem. His team mate Lando Norris, celebrating his 21st birthday, was seventh fastest.
The session was red flagged within minutes of the start after Ferrari's Leclerc slid into a bollard marking the pit lane entry.
Track workers were earlier seen chasing a stray dog reported to have been caught before any cars ventured onto the track.
Verstappen leads Red Bull one-two in slippery Turkish practice
Image: Ozan Kose-Pool/Getty Images
Max Verstappen led a Red Bull one-two in a largely meaningless Turkish Grand Prix first practice on Friday that the Dutch youngster likened to driving on ice due to slippery track conditions.
The 23-year-old produced a best lap of one minute 35.077 seconds at the end of the session on a recently resurfaced Istanbul track. The lack of grip on a cold morning posed problems for all.
His time was more than 10 seconds slower than Sebastian Vettel's 2011 pole time, when the German was with Red Bull, of 1:25.049 on Formula One's last visit to the circuit on the Asian side of Istanbul.
Thai team mate Alexander Albon was second, ahead of Ferrari's Charles Leclerc and AlphaTauri's Pierre Gasly with dominant Mercedes way down the order on a morning of wheelspins and slides.
Hamilton set for record-equalling seventh title as F1 returns to Turkey
Vettel, in his last few races for Ferrari before joining Aston Martin (Racing Point) next season, was fifth fastest.
"It’s like driving on grass - way lower grip than a wet track," commented Haas's Kevin Magnussen.
Mercedes' Lewis Hamilton, who looks set to seal his record-equalling seventh world championship in Sunday's race, was only 15th fastest and more than five seconds slower than Verstappen.
"There's no grip, it's pointless doing the start," the Briton said over the team radio when told to pit for practice starts.
Team mate Valtteri Bottas, who must score eight points more than Hamilton to stay mathematically in contention, was ninth fastest with the main priority being to get rubber down onto the track.
"It's all about tyre temperature," said Red Bull boss Christian Horner, whose team finished one-two in 2011.
"It's so, so slippery out there it is like driving on ice in many respects."
McLaren's Carlos Sainz stopped by the side of the track after earlier suffering an electrical problem. His team mate Lando Norris, celebrating his 21st birthday, was seventh fastest.
The session was red flagged within minutes of the start after Ferrari's Leclerc slid into a bollard marking the pit lane entry.
Track workers were earlier seen chasing a stray dog reported to have been caught before any cars ventured onto the track.
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