"This is an attack against President Nicolas Maduro," Communication Minister Jorge Rodriguez said following the incident that was caught during a live broadcast.

State television images showed Maduro looking up in confusion mid-speech as a bang is heard, then uniformed members of Venezuela's National Guard lined up in a parade suddenly breaking ranks and scattering.

Rodriguez said there was "an explosive charge... detonated close to the presidential podium" and in several other spots along the parade held in central Caracas.

Maduro "came out of it completely unharmed and at this moment is carrying out his normal duties and is in permanent contact with senior political officials, with ministers and with senior military chiefs," Rodriguez said.

However the blasts caused "some wounds for seven service personnel" in the National Guard. They were being treated in hospital, he said.

The parade Maduro attended was to mark the one-year anniversary of the Constitutional Assembly, a rival legislative body packed with Maduro loyalists that arrogated powers from the opposition-ruled National Assembly.