"Yes, we have information on the preparation of the attack by the troops of so-called "DPR" and "LPR" [Donetsk and Luhansk People's Republics]," Hrytsak told journalists in Kyiv on Thursday.
He said his agency was doing its best for Independence Day to be celebrated without incident.
"We have definitely enhanced the security measures as we have to do everything possible and impossible to celebrate the Independence Day in the capital and all regions peacefully," Hrytsak said.
According to him, the SBU has been put on high alert.
Hrytsak also said that the agency found explosives and agitation literature in Mykolaiv region on Thursday.
"People that wanted to create… the so-called Mykolaiv People's Republic' were detained," he said.