BEIJING - A WOMAN who burst into the Beijing Paralympics opening ceremony and tried to remove her clothes was mentally ill, organisers said on Sunday.

Press photos and TV pictures showed staff grappling with the woman, clad only in blue jeans and a bra, as she lay on the floor of the 'Bird's Nest' National Stadium during Saturday's extravaganza.

The intrusion, as 4,000 athletes were entering the stadium, was one of the worst security breaches seen during the Olympics or Paralympics.

'She tried to enter the field and remove her shirt. She was stopped by our staff,' said Ms Zhu Jing, a press officer with the Beijing organising committee.

The woman was from the southern Chinese province of Guangdong, said Ms Zhu, denying that the incident was a political protest.

'It was confirmed later by authorities that she was mentally ill,' Ms Zhu said, adding that she did not know the woman's name or age.

The woman was quickly removed from the scene, said Ms Zhu, who said she did not know whether the intruder was arrested.

China implemented stifling security for the August 8-24 Beijing Olympic Games and has maintained it for the Paralympics, which end on August 17.

Pro-Tibet activists held several brief demonstrations in Beijing throughout the Olympics before being detained by police, but venue security held firm.

However, Hong Kong pro-democracy politician Leung Kwok Hung and an associate were ejected August 9 from the Olympic equestrian venue there after mounting a protest calling for improved human rights in China.

Beijing said tight security was needed to curb possible attacks by militants from restive western China.

Security was further stepped up after the fatal stabbing in Beijing of a US Olympic coach's relative on August 9 by a Chinese man. -- AFP