Ferrari driver Charles Leclerc set the fastest time on day three of Formula 1's second pre-season testing in Barcelona, where Red Bull's Pierre Gasly crashed out of the afternoon session.

Having seen McLaren top the leaderboard for the first two days, Ferrari produced a response on the track following Sebastian Vettel's problems on Wednesday.

However, during the closing stages of the afternoon session, the Scuderia pulled up just before Turn Nine, with some smoke coming from the rear before being taken back to the pits on the recovery truck.

Nevertheless, it was an impressive display by Leclerc, who put in 138 laps having clocked a mark of one minute and 16.231 seconds from an impressive late charge on C5 Pirelli tyres before the lunch break.

Gasly, meanwhile, saw his day end early after colliding with the barrier at Turn Nine.

The Frenchman, who also suffered a crash during the first week of testing, was pictured walking away from the car, and was swiftly taken to the medical centre for precautionary check-ups.

Red Bull later put out a statement on the team's official Twitter account confirming Gasly was not hurt.

Racing Point's Lance Stroll also came to a halt on the straight between Turn Nine and 10, which saw another red flag delay.

Valtteri Bottas took over the Mercedes during the afternoon, with world champion Lewis Hamilton having earlier recovered from a spin to briefly set a fastest lap before completing 85 circuits.

Daniel Ricciardo drove 65 laps for Renault, clocking the fifth quickest of the day, while Romain Grosjean was also able to finally get some late track time following exhaust problems on the Haas car.

Like Leclerc, Alexander Albon and Stroll also went over one hundred laps, while Williams driver George Russell completed a day-high 140.

Toro Rosso's Albon was second on the leaderboard at 1min 16.882, while British teenager Lando Norris was third for McLaren.

Bottas made 96 laps, but could only set the 13th best time. Hamilton finished in 10th place following his efforts during the morning.

Ferrari, meanwhile, moved to confirm the cause of Vettel's crash on Wednesday.

The four-time world champion was taken to the medical centre and declared unhurt by his team after he went straight on at Turn Three and ploughed into the barriers due to a front-end mechanical problem.

Vettel had already registered the third fastest time during his 40 laps on Wednesday morning.

"After thorough checks we found that Seb's off yesterday was due to a (wheel) rim issue," a statement from a Ferrari spokesperson read.

"The rim had been damaged a few seconds before by an impact with a foreign object."

Friday will be the last of the eight days of pre-season testing.

The opening round of the 2019 world championship is scheduled to start in Melbourne on March 17.