However, such claims were thrown into doubt when Wang Jingqing , the deputy head of the party's powerful Organisation Department, failed to address very basic - but crucial - questions about the party conclave that have grabbed global media attention.

Wang did not provide an update on when the congress would commence. He instead repeated a party statement last year that said it was planned for the second half of this year.

When asked to confirm a widely circulated rumour that the Politburo Standing Committee, the party's innermost circle of power, would shrink from the current nine seats to seven, Wang said he did not know.

"Not even I know," he said.

Analysts said Wang's deliberate vagueness was unsurprising because it was up to party leaders, who gathered at the summer resort of Beidaihe in recent days, to make final decisions on contentious issues that have overshadowed the leadership transition.

Veteran China-watcher Johnny Lau Yui-siu said the dates must have been set at the secretive meeting in Beidaihe, which is believed to have ended.

"But according to past practice, a public announcement will not be made by Xinhua until the seventh and last plenum of the 17th Central Committee, to be held just days ahead of the next national party congress," Lau said.

Both Lau and Zhang Ming , a political analyst at Beijing's Renmin University, noted that preparations for the party congress had been severely affected by the political fallout from the Bo scandal and factional infighting within the leadership.

"The party is keen to minimise the impact of the Bo scandal and it looks unlikely that a specific date for the gathering will be made public before they wrap up the unsettled cases involving Bo, his wife Gu Kailai and his former aide Wang Lijun ," Lau said.

Gu stood trial last week in Hefei for the murder of a British businessman, while Wang Lijun's trial Chengdu , reportedly for treason, is expected sometime this week.

Wang Jingqing and his colleagues took pains yesterday to put a positive spin on the upcoming leadership reshuffle, lavishing praise on the party's efforts to promote democracy within the party and select grass-roots party members to attend the congress.

Wang said 26 migrant workers would attend and that women and young people would also be better represented at this year's congress.

Despite widespread public discontent over corruption, lack of public participation and a secretive voting process, Wang claimed that a recent survey had found that "up to 97 per cent of party members" were happy with the way congress delegates were chosen.

Deng Shengming , a spokesman for the Organisation Department, also put on a positive spin yesterday. "It's a very open, transparent electoral system, all out under the sunshine," he said.

However, local party congresses in Beijing and Chongqing, where regional delegates to the national congress were nominated and confirmed, were delayed for weeks due to unspecified political reasons.

"I haven't seen any progress or improvement in terms of the transparency of its preparations compared to the previous party gathering five years ago," Zhang Ming said. "Actually, it's even worse this time,"

Although former leaders, such as former president Jiang Zemin , are not listed as delegates, Wang said retired party elders would still be invited to attend the congress as special guests.

Olympic women's 200 metre butterfly swimming champion Jiao Liuyang , 21, is the youngest delegate, while former Beijing mayor Jiao Ruoyu , 97, is the oldest.