"I am upset about the events in Chiang Mai," he said, begging people who loved him to do so in the right way as "we are Thai people".

More than 100 Thai Rak Thai supporters in his home town of Chiang Mai protested at the arrival of Democrat leader Abhisit Vejjajiva and other members of the party, who had planned to hold a rally at the city's university.

He said he hoped that was the last time he would see such an episode. "Each side volunteers to work [in politics], and they have different methods. However, every party has to do what is right for the country, so I want every party to consider this issue," he said.

Thai Rak Thai member Suranand Vejjajiva said his party was sorry about the events of Thursday. He said the three incidents - at the Election Commission, The Nation building, and the Chiang Mai attacks on the Democrat members - should not have happened.

"All sides should remain composed. Today our country was wounded too much. I think all parties have to compromise to solve the problems," he said.

Suranand also dismissed suggestions that his party was behind the attacks on the Democrat rally. "Our party was not behind the incident, and we are concerned with the political situation. That is why we cancelled our speech at Lumpini Park," he said.

Chiang Mai Mayor Boonlert Buranooprakorn, a brother of former Thai Rak Thai MP Pakorn Buranooprakorn, yesterday also denied that he was behind the occurrence. He said he had learnt of the attack from television.

"As far as I know, the attack was a response to a female protester being pushed by a Democrat supporter in the audience. This resulted in members of the pro-Thaksin camp becoming angry and rushing the stage," he said.

He said he had asked his deputy and other local municipality members who had been seen with the pro-Thaksin protesters what their role in the violence had been.

"He [the deputy mayor] explained that he had gone to the Democrat meeting because he had to look after a mobile toilet which had been set up for members of the audience," said the mayor.

Abhisit said the incident was a challenge to the law.

"The government and the police must prove with this case that mob rule is not above the law," he said.

He said that while the party had not yet filed a complaint "we will not ignore this case. I will certainly [file a complaint] under the law".

Abhisit admitted that the incident had made Democrat supporters angry. However, he said that they did not think badly of the people of Chiang Mai as it was just a small group that had been managed. The Democrat leader also expressed concern that the event may cause dis-harmony in the country.

Chuan Leekpai, a senior adviser to the party, said he was not angry with the locals who attacked him and other party members because he knew they had been ordered to do so by other people.

"We understand them. People from Chiang Mai are not aggressive. Some cried with me and told me how sad they were about the incident," Chuan said.

However, he said the party was concerned about a lowering of restraint among supporters of different parties and pleaded for other people, especially in the South, not to behave the same way. "Thai people have to live in harmony," he said.

Most party members are likely to take a cynical view of the incident, believing those responsible for the violence were set by up by powerful people, he said.

Meanwhile, a number of Democrat supporters from Trang, in the South, yesterday expressed their unease at the incident by sending an open letter to the Thai Rak Thai Party leader, demanding that he take responsibility.

Residents of Satun said the incident had made them furious and that as a result they would not vote for Thai Rak Thai in tomorrow's election. Some said they would put an "x" in the "no-vote" box on the ballot.