Costa Rica's government has asked Washington to explain why it devised a secret 'Cuban Twitter' social media network from inside the Central American nation's borders.

Costa Rica President Laura Chinchilla confirmed on Thursday that she approved a diplomatic note her government sent to the US Embassy in San Jose asking about the social media network.

"The appropriate (diplomatic) note was sent to make our position known and from our point of view there is nothing more to add," Chinchilla told reporters at a government event in San Jose.

The US Agency for International Development (USAID) created ZunZuneo to stir political unrest in Cuba, but its users were unaware it was backed by the US government.

In early April, the Associated Press reported that ZunZuneo's development team initially operated out of Central America.

A USAID manager supervised the work of US contractor Creative Associates International from an office in the capital San Jose.

The US government has denied that the program was secret or that it had a political agenda.

Documents obtained by the AP show that contractors working on ZunZuneo went to extensive lengths to hide its ties to the US, using foreign companies and computer servers paid for via a bank account in the Cayman Islands.

They did so after acquiring more than 400,000 mobile phone numbers from Cuba's state-run telecommunications provider.

AP TELEVISION

1. Wide of Laura Chinchilla, Costa Rica President speaking at an event of the Central American Bank for Economic Integration

2. Mid of Chinchilla speaking

3. Wide of event

4. Chinchilla speaking

5. Chinchilla leaving event and stopping to greet someone

6. Chinchilla talking to media, with Costa Rica Communications Minister Carlos Roverssi to her right (with yellow tie)

7. SOUNDBITE (Spanish) Laura Chinchilla, Costa Rica President:

"The appropriate (diplomatic) note was sent (to the US Embassy in Costa Rica) to make our position known and from our point of view there is nothing more to add."

8. Roverssi listening to Chinchilla as she talks to media

9. Close of Roverssi

10. Roverssi listening to Chinchilla as she talks to media

11. SOUNDBITE (Spanish) Carlos Roverssi, Costa Rica Minister of Communication:

"Look, when we learned through the AP (about social media network ZunZuneo), which was the (news agency) that brought this information to light, we officially requested that the government of the United States clarify the facts, as they have been reported. The government of the republic (Costa Rica) was unaware of the issue (meaning ZunZuneo's existence), the issue came about in 2008 and we are waiting for the response from the government of the United States."

12. Roverssi leaving event