Opposition leader Alexei Navalny has denied allegations that he breached a court order by traveling outside Moscow over the weekend.
The Investigative Committee threatened Monday it would seek tighter restrictions against Navalny, who is facing embezzlement charges, if he violated the travel ban again.
Investigators said he broke the rules by driving beyond Moscow's borders during the weekend.
The committee could request "a more severe punishment" if Navalny violated the travel ban again, an Investigative Committee spokesman told RIA Novosti.
Navalny denied the accusation and posted a copy of the bail conditions on his LiveJournal site. He said the document showed that the court allowed him to travel around the Moscow region, and not simply remain within the administrative borders of the capital.
He wrote that the original agreement, which did limit him to Moscow, was amended to include the Moscow region because he had to cross the city's outer MKAD ring-road to reach his home.
"The Investigative Committee apparently forgot that my agreement covers Moscow and the Moscow region," Navalny wrote on his Twitter account.
He said that he was stopped by traffic police on Sunday as he was going to see his parents outside Moscow.
Navalny and his brother Oleg have been accused of organizing a scheme to defraud the local branch of cosmetics manufacturer Yves Rocher.
In October, Navalny was handed a five-year suspended sentence after a regional court convicted him of stealing $500,000 worth of timber.
Navalny was at the forefront of the mass protests against President Vladimir Putin in 2011 and 2012, and came second in the mayoral elections in September.