BOGOTA, June 27 (Reuters) - Ricardo Roa, chief executive of Colombian majority state-owned energy company Ecopetrol , said on Thursday flexibility in government rules was needed to allow a sale of gas blocks and have them producing in 10 years.

A pipeline to import gas from Venezuela could be physically ready within 10 to 14 months, but a license from the U.S. Treasury Department's Office of Foreign Asset Control is needed for operations to go ahead, Roa told journalists in Cartagena.

"If there is no license, there is no transaction," he said.

The U.S. has reimposed

oil and gas sanctions

on the Venezuelan government in response to President Nicolas Maduro's failure to meet his election commitments.

Colombia could face a deficiency equivalent to 8% of the country's daily consumption by 2025, requiring measures to increase supply, Ecopetrol studies showed.

"We need regulation and flexibility from the ministry (of mines and energy) to sell gas blocks," Roa said.

The blocks need to be able to produce between 145 and 280 giga-British thermal units of gas per day, he said.

Last month, Colombia's National Hydrocarbon Agency reported that the Andean country's gas proven reserves had fallen to 2.4 trillion cubic feet, equivalent to 6.1 years of consumption.

Colombia's government and Ecopetrol have touted importing gas from Venezuela via the Antonio Ricaurte pipeline, which has been inactive for years and needs maintenance and repair work.

(Reporting by Oliver Griffin and Luis Jaime Acosta; Editing by Leslie Adler and Richard Chang)