CARACAS, Jan. 8 (Xinhua) -- The Venezuelan government on Tuesday said it has stepped up pressure on Colombia to extradite suspects involved in a failed assassination attempt against President Nicolas Maduro.

The Foreign Affairs Ministry said it made two verbal requests on Monday to its Colombian counterpart, asking for extradition of citizens involved in the attempted assassination on Aug. 4, 2018.

The latest requests "bring to 14" the number of communications Venezuela has initiated with Colombia on the matter, the ministry said, adding "no diplomatic response has been received."

During an outdoor event on Aug. 4 last year, two drones carrying explosives flew close to Maduro, who was giving a speech, and detonated them.

Maduro was unharmed but several members of the military sustained injuries.

Maduro said in the wake of the incident that investigation suggested it was linked to Colombia and the United States, where many Venezuelan exiles live.

Both countries have denied links to the drone attack.