BEIJING: The United States and Britain set the early pace at the Paralympics Sunday as Olympic swimmer Natalie du Toit claimed her first gold and Chinese officials played down an embarrassing security breach.

On day one South Africa’s du Toit, who finished 16th in the Olympics women’s 10 kilometres swim, timed 1min 6.74sec in the 100m butterfly in her category, one of 16 golds on offer in the pool.

The 24-year-old amputee is aiming for four more wins to match her 2004 gold tally, but warned sweeping each of her five events would be difficult.

Du Toit won five golds and a silver at the Athens Paralympics. She lost her left leg in a road accident in 2001, after narrowly missing qualification for the Sydney Olympics a year earlier.

Chinese organisers meanwhile said a woman who burst into the opening ceremony and tried to remove her clothes was mentally ill and dismissed suggestions she was mounting a political protest.

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. The United States and Britain both finished the opening day with four golds.

Britain picked up where they left off in the Olympic cycling, grabbing three track golds. Britain and Australia notched up three world records apiece.

Britain’s Darren Kenny knocked almost six seconds off his own world record in the qualifying round of the men’s individual pursuit before going on to take gold.