Prime Minister Surayud Chulanont yesterday decided to shorten his planned visit to China following Thursday's royal speech expressing concern about the potential for trouble triggered by next Wednesday's verdicts on electoral fraud.

"I will return from China on the evening of May 29, instead of May 31 as initially planned," he said.

The Constitution Tribunal has scheduled May 30 to hand down two decisions on separate electoral fraud cases involving the Thai Rak Thai and Democrat parties.

Surayud said he was worried about the volatile situation, even though he did not suspect a mass protest to erupt because of the two judicial rulings.

He urged all sides to be mindful of His Majesty's remarks on the situation.

"Every Thai citizen should cooperate to solve problems that have become disheartening to the King," he said.

He said all sides should try to reconcile their differences rather than resort to violent confrontation.

"I firmly believe the best way to get out of the political predicament is through talks, otherwise the country will plunge into endless chaos," he added.

He said Council for National Security (CNS) chairman General Sonthi Boonyaratglin shared his view that this month was a "critical period" that must be overcome in order to successfully complete the political transition.

Under his revised schedule, the prime minister will leave Bangkok on Monday.

He is to hold one-day talks with Chinese leaders in Beijing and witness the signing of three bilateral agreements.

On Tuesday, he will make a stopover in Kunming to discuss plans to construct a rail link between Yunnan and northern Thailand.

Meanwhile, Defence Minister Boonrawd Somtas yesterday warned that soldiers and security officials were having to step up their vigilance in view of increased political volatility amid the transition back to democratic rule.

"I have detected many political time bombs, including one this month because of the verdict on electoral fraud [cases] and another on the completion of drafting the new constitution," he said.

The CNS has been tasked with keeping the peace and pre-empting a crisis that could disrupt the political transition, he added.

He said "ill-intentioned elements" were intensifying their efforts to infiltrate and turn Bangkok into a mass protest site.

He said he was heartened that Thursday's royal speech would help to pacify rival sides, though the situation remained very volatile.

However, Constitution Drafting Committee chairman Prasong Soonsiri, yesterday warned of political turmoil following the tribunal's rulings.

He said turbulence would be ignited by politicians and former MPs who stood to lose from the rulings.

Prasong recommended the government declare a state of emergency if it considers any trouble is more than the police can cope with.

Meanwhile, Jatuporn Promphan, a founder of the satellite-based People's Television (PTV), said the station would go ahead with its plan to hold a mass demonstration at the Royal Plaza on May 31.

Further, PTV leader Veera Musigapong will petition His Majesty asking for the restoration of the 1997 constitution to allow the next general election to be organised immediately.