Mexico City, Oct 16 (IANS): The Mexican government is demanding a "clear and precise" answer from the US for allegedly spying on President Enrique Pena Nieto, Foreign Minister Jose Antonio Meade said.

"We want to demand an investigation and a demarcation of responsibility for alleged acts of espionage," Xinhua quoted Meade as saying 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 organisations as it had interfered in Mexico's internal affairs, some senators argued.

The alleged espionage was leaked by former US National Security Agency contractor Edward Snowden, who said Washington had spied on Nieto before he was elected president in June 2012.

Mexican authorities have already disagreed with the US in terms of security and migration issues, Meade said.

"In the dialogue with the US, we have addressed the differences in a timely and mature way that inevitably arise in a close relationship," he said.

After the disclosure of the alleged espionage, Mexico summoned the US ambassador to explain the accusation. Nieto also discussed the issue with his US President Barack Obama during a private meeting held in Russia early September.

However, some opposition senators believed that Mexico should have a "strong" reaction and demanded more explanations from the US.