KIEV, Aug. 25 - Ukraine’s law enforcement authorities may open a criminal investigation against Oleksandr Turchynov, the closest ally of imprisoned former Prime Minister Yulia Tymoshenko, for leading an opposition march on Wednesday.

Turchynov, together with other opposition leaders, led a peaceful march of about 3,000 protesters on Independence Day towards the offices of President Viktor Yanukovych.

The crowd was stopped by a massive riot police force several blocks from the place of the opposition rally, and was later dispersed.

“I can’t rule this [investigation] out,” Anatoliy Lazarev, the chief of staff at the Internal Affairs Ministry, said at a press conference. “Everything will be done according to the law.”

The investigation, and possibly the arrest of Turchynov, will be a significant blow to the opposition groups, which have been failing to generate massive street protests so far.

The comment comes as the Kiev Prosecutor’s Office on Thursday opened investigation into the alleged violation of a court ruling that had banned opposition marches in downtown Kiev on the Independence Day.

“As a result of their resistance [to police] the protesters have injured six police officers,” the Kiev Prosecutor’s Office said in a statement.

The opposition groups planned to start massive street protests on Wednesday, but had failed to generate significant support.

Hanna Herman, a senior advisor to Yanukovych, said Wednesday that the authorities will be deploying as many police offices as necessary to prevent what she called “fighting and bloodsheds.”

The failure to summon up more protesters for igniting the sustainable protest shows that popular support for Tymoshenko has remained weak even despite her arrest on August 5.

Tymoshenko was arrested on contempt of the court charges as she is on a trial for negotiating a controversial natural gas agreement with Russia in January 2009.

Turchynov, the No. 2 in command at Tymoshenko’s Batkivshchyna opposition party, has been the key ally of the former prime minister, and for years has been her campaign chief.

Reacting to the warning that his actions may be investigation by law enforcement, Turchynov said this was the sign the government has been restricting democracy.

He said the march was stopped by police on the route that had been earlier approved by a court for the opposition groups.

Police has apparently moved to stop the crowd after hearing Turchynov’s calls at the rally for marching towards the offices of Yanukovych.

“Not even all authoritarian countries open criminal cases for making a speech at a rally,” Turchynov said. “But it appears that in our country a speech may be a reason for opening the criminal case. Let me congratulate the leaders of the Interior Ministry and the leaders of our country.” (tl/ez)