Kim Jong-un’s influential younger sister has appeared in public for the first time in more than 50 days, attending the “Mass Games” propaganda displays that the North Korean leader later criticised for their “wrong spirit”.

Kim Yo-jong, who was by Kim’s side throughout both of his meetings with the US president, was shown seated next to her brother at the event in Pyongyang on Monday evening.

Reports suggested that he had ordered her to keep a low profile after the failure of his recent nuclear summit with Donald Trump.

An image released by North Korea’s official Korean Central News Agency shows Kim Jong-Un waving at the games and his sister, far left Photograph: Kcna Via Kns/AFP/Getty Images

Kim was also accompanied by his wife, Ri Sol-ju, and senior North Korean officials at the 150,000-seat May Day Stadium to watch thousands of performers on the opening night of the event.

Despite his sister’s apparent appreciation for the gymnasts and dancers’ efforts, the North Korean leader was unhappy with the performance.

The state news agency KCNA said Kim had “called creators of the performance and seriously criticised them for their wrong spirit of creation and irresponsible work attitude, pointing to the contents and forms of works”.

Noting that artists “have a very important duty in socialist cultural construction,” Kim “set forth important tasks for correctly implementing the revolutionary policy of our Party on literature and art,” KCNA added.

Following rehearsals over several months, vast numbers of people in colourful costumes took part in the precision synchronised performance, portraying moments from Korean history and modern life.

North Korean artistic performances are closely watched by observers for clues as to the authorities’ priorities, such as whether they are highlighting economic achievements or military progress.

Mass Games 2019 opening night. North Korea. Photograph: Instagram

The senior government officials present at the games included Kim Yong-chol, the North’s counterpart to US secretary of state, Mike Pompeo, in nuclear talks.

South Korea’s Chosun Ilbo newspaper had mistakenly reported that Kim Yong-chol had been sent to a labour camp after a second summit between Kim Jong-un and US president Donald Trump broke up without agreement in Hanoi in February.

Unmentioned in the KCNA story was Kim Hyok-chol, North Korea’s special envoy to the US who – according to the Chosun Ilbo newspaper – was executed by firing squad for “betraying the supreme leader” after he was “won over to the US” during pre-summit negotiations.

On Tuesday, CNN, claimed that Kim was alive but in custody and under investigation for his role in the failed summit. Citing one of several unnamed sources, CNN said his fate had not been decided, but that he could still face “heavy punishment”.

Kim Yo-jong had not appeared in public since April, when she attended supreme people’s assembly, according to South Korea’s Yonhap news agency.

Speculation that she had been disciplined after Kim and Trump failed to reach an agreement at their February meeting in Hanoi rose after she was absent from Kim’s entourage when he traveled to Vladivostok in April to meet Vladimir Putin, Yonhap added.

The show, known in the North as a Grand Mass Gymnastics and Artistic Performance, is titled The Land of the People and is expected to run for five months, into October.

Traditionally, the scenes on the arena floor take place against an ever-changing backdrop, made up of thousands of children turning the coloured pages of books in sequence to create giant images rippling across one side of the stadium.