LIMA (Reuters) - Peru's President Ollanta Humala said on Saturday that he was recalling the Peruvian ambassador from Chile and would not accept "unfriendly acts" from the neighboring Andean country amid suspicions of spying.

Peru also sent a letter of protest to Santiago following revelations this week that two Peruvian naval officials are being tried and a third investigated for allegedly spying for Chile.

"We're waiting for an answer from the Chilean government," Humala told reporters on the sidelines of an event.

Chile had said in a statement on Friday that it does not promote or accept spying.

Humala, who previously warned that confirmation of the spying would damage ties, said his evaluation of the Navy's evidence merited a firmer position toward Chile.

"This government is not going to accept unfriendly acts of this nature," Humala said. "And even less so from countries with which we've been working in a sustained way."

The souring of relations comes just over a year after an international court decision settled a lingering border dispute between the two countries that had raised expectations their long history of mutual distrust was past.

"It's a delicate issue, a regrettable one," Humala said. "It's affecting the work that has been done at the level of the foreign ministry to strengthen bilateral relations."

In a statement on the ministry website, Lima urged Santiago to carry out an investigation to find those responsible for the spying and to guarantee it would not happen again.

The head of Peru's military courts said that the trial of the two naval officers might not wrap up until August and that ongoing investigations are probing whether higher-ranking officers were also involved.