Lorenzo Insigne gave Napoli hope with a penalty to make it 3-2 on aggregate.

But Gerard Pique scored and Pierre-Emerick Aubameyang fired into the top corner from Traore's pass, with Matteo Politano netting a late consolation.

Barcelona will discover their last-16 opponents - one of the Europa League group winners - in Friday's draw.

Both sets of players stood with a banner saying 'Stop War' before kick-off in response to Russia's invasion of Ukraine.

Barcelona and Napoli had an anti-war message before kick-off

Premier League recruits help Barcelona shine

Barcelona must now be considered one of the favourites to win the Europa League.

Results have picked up since Xavi replaced Ronald Koeman and their front three, all January signings from the Premier League, sparkled again.

Napoli could not deal with their pressing from the front in the first half as Barca took control of the tie.

Traore, on loan from Wolves, has now set up four goals in five games for Barca. He brushed off several defenders to run from the halfway line and feed Alba.

Ferran Torres, a £46.7m signing from Manchester City, then backheeled the ball to De Jong to claim their second in the 13th minute.

After Insigne's spot-kick following a foul on Victor Osimhen, Pique turned in Barca's third just before half-time to restore their two-goal advantage.

Traore then passed from the right wing and De Jong stepped over the ball for Aubameyang to fire in an excellent shot for the fourth.

The Gabon international, who joined on a free transfer from Arsenal, had also scored a hat-trick at the weekend against Valencia.

Politano's low finish three minutes from time was too late for Napoli to affect the outcome.