The Mexican government is demanding a "clear and precise" answer from the United States for allegedly spying on President Enrique Pena Nieto, Foreign Minister Jose Antonio Meade said on Tuesday.

"We want to demand an investigation and a demarcation of responsibility for alleged acts of espionage," Meade said during a hearing in the Senate, whose members have shown dissatisfaction with the government's previous response to Washington.

The response was inadequate and the case should be discussed with international organizations as it had interfered in Mexico's internal affairs, some senators argued. The alleged espionage was leaked by Edward Snowden, who said Washington spied on Nieto before he was elected in June 2012.

Mexican authorities have already expressed disagreement with the US on security and immigration issues, Meade said.

Xinhua