Police have said they are "monitoring" activity around showman David Blaine's starvation stunt near Tower Bridge in London.
Blaine said he wanted to push himself to the limits
It follows reports of onlookers throwing eggs and bananas at Blaine's plastic box, and shining laser pens at the 30-year-old New Yorker.
Police say they are responding to any reports of possible offences but have made no arrests.
Blaine is attempting to spend 44 days suspended in the box without food.
A Metropolitan Police spokesman said the force had been contacted by Blaine's own security staff following incidents on Tuesday.
He had reportedly been pelted with eggs, fruit and chips, while a female spectator partially stripped off beneath his box.
"Police were alerted at times throughout the day," said the Met spokesman.
Some local residents have complained about traffic coming to a standstill on Tower Bridge as motorists slow down to look at the stunt.
Blaine's endurance challenge - dismissed by some critics as an illusion - is being televised by Sky One and Channel 4.