Barcelona continued their 100% start to life in La Liga in bizarre circumstances, beating Las Palmas 3-0 at an empty Camp Nou. The club had asked for the match to be postponed due to protests across Catalonia over the controversial Catalan independence referendum in which more than 750 people have been injured, many in the Spanish city.

That request was rejected and Barcelona, threatened with a six-point deduction according to their club president, Josep Maria Bartomeu, if they did not play the game, took the decision 20 minutes before kick-off to play it behind closed doors, leaving thousands of supporters stranded outside. A statement from La Liga said the match should take place as normal because the security and safety of fans had been “guaranteed” by the Catalan police.

“We have not been able to find a way to postpone it,” Bartomeu said. “From there, all together, directors, executives and players met and we decided, exceptionally, to play the game behind closed doors. Els Mossos [the Catalan police force] told us the game could be played normally. Playing this way, with the stadium empty, the club shows its disagreement [with the decision not to postpone the game]. The league told us we would lose six points, three from today and three as a penalty.”

Las Palmas had the national flag embroidered on to their match-day shirts to show their support for a united Spain while Barcelona emerged for the warm-up wearing a yellow-and-red-striped shirt – the colours of the Estelada flag associated with Catalan independence. Earlier on Sunday the defender Gerard Piqué tweeted a photo of him voting in the referendum. “Together we are unstoppable defending democracy,” he said. After the match, speaking to the gathered media, a teary-eyed Piqué described the match as “the hardest game to play”.

The result of the match itself ensured Barcelona extended their perfect start to the season, earning a seventh league win. Ernesto Valverde’s side have now scored 23 goals this season, conceding only twice. And by keeping Las Palmas at bay on Sunday afternoon Barcelona recorded their 1,000th La Liga clean sheet.

Amid an eerie and strange atmosphere Barcelona started slowly and Las Palmas dominated much of the first half. Jonathan Calleri, the former West Ham United striker, rattled the post three minutes before the interval after good work by Oussama Tannane, who unselfishly laid the ball off.

But at half-time Valverde, the Barcelona manager, sought personnel changes, introducing Andrés Iniesta and Ivan Rakitic in place of Aleix Vidal and Paulinho. The latter impressed in the first half but headed wide after arriving late into the box to meet Sergi Roberto’s deep cross, while the substitute Iniesta was later withdrawn with a hamstring injury. Barcelona began the second period with much more intent and were rewarded for their efforts after 49 minutes, with Sergio Busquets glancing home at the near post from Lionel Messi’s corner.

Then Barça grew in stature, with Rakitic twice seeing his shots blocked by Mauricio Lemos, the Las Palmas defender. But Messi came up with a second goal, rounding the goalkeeper, Leandro Chichizola, with ease after latching on to Denis Suárez’s defence-splitting reverse ball. Seven minutes later the game was over, with Messi starting and finishing a slick move for his 14th goal of the season.

After Rakitic fed Luis Suárez, the Barcelona forward flicked the ball with his first touch into the path of Messi, who tucked it home. Luis Suárez did find the net himself but his acrobatic effort was ruled out after he was adjudged to have committed a foul in the build-up to his overhead kick.