Buildings cracked and collapsed as residents rushed into the streets after two earthquakes measuring 7.2 and 7.5 in magnitude struck northern Venezuela less than a minute apart, according to the United States Geological Survey.

Offers of rescue support and aid flooded in from around the world as interim president Delcy Rodriguez reported at least 164 dead and over 970 hurt.

The state of La Guaira north of Caracas was hit particularly hard, and residents stumbled through debris calling out the names of loved ones or tried in vain to rescue the injured.

"There's a spot where a young woman named Jennifer, from the 11th floor, answers me. However, we don't have any tools; we have no way to help," said Antonio Bermudez, whose building collapsed in La Guaira.

Elsewhere in the rubble, a father and his son were using a pickaxe and a crowbar to try and pry away massive slabs to get to two of his other sons, said Bermudez.

"They're still alive... there's nothing more we can do. We're telling them not to strain their voices, to take short breaths, in the hope that at least the three of them who are there will be rescued."

The coastal city was without electricity, and many residents spent the night in the streets or searching for their relatives, according to AFP reporters.

The strongest quake to hit Venezuela in 126 years will require "massive collective efforts," the United Nation's aid chief Tom Fletcher said in a statement. He said the UN was "fully mobilised" to send aid.

Threatening to complicate relief efforts, the international airport near Caracas was closed due to "serious damage," Rodriguez said.