Issues surrounding territorial disputes in the South China Sea are set to dominate a key annual defence forum in Singapore starting today - but leading Chinese military brass will not be taking part. General Liang Guanglie, the defence minister, last year became the highest-ranked Chinese official ever to attend the informal Shangri-La Dialogue, but this year's People's Liberation Army team is headed by Lieutenant General Ren Haiquan, vice-president of the PLA Academy of Military Science, the Defence Ministry confirmed yesterday. The organiser, the London-based International Institute of Strategic Studies, is still insisting it will be the biggest gathering yet, with officials from 28 nations attending. They include United States Defence Secretary Leon Panetta and General Martin Dempsey, chairman of the US Joint Chiefs of Staff. Indonesian President Dr Susilo Bambang Yudhoyono will give the keynote address tonight. Delegates - including regional ministers, military brass, scholars, intelligence analysts and arms manufacturers - will be covering a range of regional issues. The South China Sea is slated for discussion tomorrow. Confirming Ren's presence, Ministry of National Defence spokesman Yang Yujun said officials from the defence and foreign ministries would also be attending. With Panetta due to visit Vietnam and India after Singapore, the Foreign Ministry yesterday urged Washington to play a 'positive and constructive role in the region'. 'We also hope the US will respect China's interests in the region,' said ministry spokesman Liu Weimin. As an informal forum, the Shangri-La Dialogue meetings traditionally spark more heated debate than more tightly choreographed formal diplomatic gatherings, with Chinese officials and scholars frequently rising from the floor to challenge US strategic assumptions. It has also brought many issues to the surface before they burst onto the diplomatic arena. In 2010, for example, mounting US concern over tensions in the South China Sea was evident before it was formally raised by US Secretary of State Hillary Rodham Clinton at the formal Association of Southeast Asian Nations Regional Forum a month later. While General Liang won applause at last year's event for a lengthy speech and taking questions afterwards, his remarks on the South China Sea faced immediate challenges from his Filipino and Vietnamese counterparts. Liang and Philippine Defence Secretary Voltaire Gazmin agreed both countries should show restraint over the tense stand-off at Scarborough Shoal - known as Huangyan Island in China. Their Vietnamese counterpart, General Phung Quang Thanh, privately told his Asean counterparts there was a 'possibility of military conflict' in the South China Sea, unless countries showed restraint, according to diplomats. He urged Asean to take the lead in resolving the issue, later adding that it was the sole problem remaining between Hanoi and Beijing.