Aston Martin's Fernando Alonso was fastest in Thursday's floodlit second practice for the Saudi Arabian Formula One Grand Prix after Red Bull's reigning champion Max Verstappen set the afternoon pace.

George Russell was second on the timesheets for Mercedes, 0.230 slower than Alonso's one minute 28.827 second effort, with Verstappen third and 0.331 off the Spaniard's best.

The second session was delayed briefly due to reported loose drain covers, a problem that beset testing in Bahrain last month and also in Las Vegas last November. This time the matter was swiftly resolved.

Alonso had been second in the first session, 0.186 slower than triple world champion Verstappen's 1:29.659.

"I feel good. Obviously, it's only free practice," said Alonso. "As we saw last year and also in Bahrain, we are faster in free practice than in qualifying. I think we run different strategy in terms of fuel loads, engine modes and so on."

"We keep our programme, not really any issues with the car...definitely a good Thursday for us."

Russell said the car had not been in the perfect window and the second session was a little bit scrappy.

"The times looked good on the single lap, and we're not too sure yet where we're at on the long runs," he added.

The second round of what is a record 24-race season is being held at Jeddah's Corniche circuit on Saturday night, one day earlier than usual, to accommodate the start of Ramadan on Sunday night.

Alonso's lap time compared with last year's fastest in second practice, a 1:29.603 also by Verstappen on the soft tyres.

"Looking to qualifying I am feeling good; it will be tight but we are happy with our performance today and looking forward to tomorrow," said Verstappen.

Ferrari's Charles Leclerc was fourth quickest in practice two after Russell had filled that position in the afternoon.

Leclerc's team mate Carlos Sainz took part in both sessions after feeling unwell on Wednesday but curtailed his media duties. The Spaniard was sixth and seventh respectively.

"The track, it's like Mario Kart. There are plastic bags everywhere," reported Leclerc over the team radio in the afternoon.

Red Bull's Sergio Perez, last year's winner in Jeddah, was third and fifth fastest.

The evening session saw Aston Martin's Lance Stroll sixth, seven times world champion Lewis Hamilton eighth for Mercedes, Pierre Gasly ninth for Alpine and Oscar Piastri 10th for McLaren.

Hamilton collected a warning from stewards for blocking Williams' Logan Sargeant in the second session, with Mercedes fined 15,000 euros ($16,000).

Stewards said it was clear from the team radio that Mercedes had failed to warn Hamilton that Sargeant was approaching at speed at turn 11, where visibility is impaired, and there would have been a serious crash had the American not gone off track.

"I didn't realise someone was on a lap. I was trying to get out of the way for Sainz and all of a sudden there was a Williams there," Hamilton said over the radio.

($1 = 0.9136 euros)

(Reporting by Alan Baldwin in London, editing by Toby Davis and Ed Osmond)