Three senior Shenzhen officials are being investigated as part of a Communist Party disciplinary probe that last week snared the border city's mayor, Xu Zongheng, sources said yesterday. The three include at least one vice-mayor. One source also said the trigger for the investigation of Mr Xu was the city's decision last year to drop a winning design for a stadium - submitted by the designers of Beijing's 'Bird's Nest' Olympic arena - in favour of another that failed expert assessments. The anti-corruption investigation was discussed yesterday at an internal meeting led by Guangdong party secretary Wang Yang , the sources said. It was announced at the meeting that the three other officials were being investigated. Separately, government sources said Liu Yupu would soon leave his post as Shenzhen party secretary to become chairman of the Guangdong committee of the Chinese People's Political Consultative Conference. That position was held by Chen Shaoji until April, when he was detained over corruption related to Wong Kwong-yu, the billionaire entrepreneur behind the Gome electrical chain who is under arrest for share-price manipulation. Mr Liu's departure is not a surprise and is apparently not linked to the latest corruption scandal. Mr Liu, who will reach the retirement age of 60 in August, has for some time been tipped to become the Guangdong CPPCC chairman. Nevertheless, it means that Shenzhen will undergo a major leadership reshuffle at a time when the city is facing great economic difficulties because of the global downturn. Vice-mayor Xu Qin will be in charge until a new mayor is appointed. Several sources said yesterday Xu Zongheng had tried to commit suicide on Sunday night. He has been taken away from Shenzhen and is in custody at an undisclosed location. Xu Zongheng was formally put under shuanggui - a form of detention imposed by the Communist Party on officials - on Friday, the South China Morning Post reported. Xinhua officially confirmed the report yesterday. It did not disclose further details. But a source said it was the decision on the stadium for the World University Games, which Shenzhen will host in 2011, which had caught the eye of the anti-corruption authorities in Beijing. The investigators locked onto Xu Zongheng and started to investigate his other questionable dealings. A source said he was involved in corruption problems related to the Taoyuanju property project, a big public-housing development. They had also found he was linked to Wong, the Gome chief. Several sources said anti-corruption investigators had been working on the case for months. The trigger for it was the decision of urban planning authorities in March last year to ditch the winning design for the Shenzhen Bay Stadium in favour of a rival design that is twice as costly. A panel of experts picked a 'seashell' design by Swiss firm Herzog & de Meuron and the China Architecture Design Institute. But two weeks later, the winners were told their plans needed further expert assessment together with a design called the 'spring cocoon'. The experts still favoured the 'seashell' but the authorities picked the rival design. The chief architect of the seashell, Li Xinggang , was later invited to provide information to the central government.