Last Saturday, the presidential motorcade encountered a traffic jam during one of his outings as chairman of the ruling Kuomintang, the paper said. Instead of moving away to the shoulder of the road, his security detail used a megaphone to order cars in front to leave the fast lane, according to the paper.

Ma has been repeatedly criticized for failing to keep a proper separation between his functions of head of state and party chairman in the run-up to the Dec. 5 county elections.

Excessive security was inconveniencing the public and harming the fairness of the election, the paper quoted opposition Democratic Progressive Party Chairwoman Tsai Ing-wen as saying.

The Presidential Office said that bodyguards and police had started discussions about how to improve the handling of traffic problems by the motorcade in the future.

Presidential spokesman Wang Yu-chi said Ma had already done his best to improve the situation. After he came to office last year, he demanded to change the rules in order to minimize inconvenience to the public, Wang told a news conference yesterday afternoon. Instead of changing the traffic lights at all intersections during a trip through the city, the motorcade would now only control a limited number of intersections, he said.

The spokesman was not willing to comment on reports that Ma was not in his car at the time of the incident but traveling south to Chiayi.

At the Legislative Yuan, national police chief Wang Cho-chiun said that driving in the fast lane had been the practice under previous presidents like Lee Teng-hui and the DPP's Chen Shui-bian as well.

Wang said security staff would not make a distinction between Ma on a presidential mission or a private outing, since in either case he was still the president. The National Security Bureau said it was just protecting the head of state's security by keeping the motorcade moving forward, and not forcing other motorists out of the way.

This would not happen again during an election campaign, Interior Minister Chiang Yi-huah told lawmakers.

However, the authorities said a picture accompanying the Liberty Times story was only a reconstruction, as the stretch of road where the incident reportedly happened, between Nankan in Taoyuan County and Linkou in Taipei County, did not have a shoulder to drive on.