MANILA - Foreign Affairs Secretary Alan Peter Cayetano and former President Benigno "Noynoy" Aquino III figured in a word war Friday over the South China Sea dispute.

Cayetano, in an open letter, said it is "regrettable" that the former president chose to play with words including comparing their haircuts in discussing the Philippines' handling of the sea row.

The foreign affairs chief's comments were in response to Aquino's earlier remarks that the former should be as "transparent as his hairstyle."

"While we both lost some of our hair, your administration lost control of Scarborough and a great opportunity to expand tourism, infrastructure and agriculture," Cayetano said.

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It was during Aquino's time as president that the Philippines had a standoff with China at the Scarborough Shoal, traditional fishing grounds off Zambales.

• READ: 5 facts on Scarborough Shoal

Cayetano went on to blame Aquino, former Foreign Affairs Secretary Alberto del Rosario, and opposition Senator Antonio Trillanes IV over their approach to the dispute which allegedly led to the loss of several opportunities for the Philippines.

The top diplomat again questioned Aquino on how Manila lost control of the Scarborough Shoal in 2012 and who was in command of the situation.

"We note that there seems to be a denial all around of any negotiated joint withdrawal of both Chinese and Philippine vessels from the shoal. Was there an agreement? Brokered by who?" he asked.

Cayetano again questioned how Trillanes brokered backchannel talks with China and asked for details of Aquino's previous meeting with former United States President Barack Obama.

"Sen. Trillanes had refused to reveal the purpose and nature of his trips when asked during a Senate session by then Sen. (Juan Ponce) Enrile. Instead, he walked out and invoked presidential prerogative so he would not be compelled to respond," Cayetano, a former senator, said.

"What did you discuss with President Obama? He reportedly affirmed to Japan that the mutual defense treaty will be put into action if the Senkaku islands are threatened. Did Mr. Obama tell you that the US does not get involved with territorial disputes like in the WPS (West Philippine Sea)?" he added.

The West Philippine Sea is the country's exclusive economic zone in the South China Sea.

Cayetano then dared Aquino to answer his questions in lieu of "transparency."

"If, indeed, transparency is important to you as you claim, then consider your early response to these questions as crucial," he said.

"Our people await your response to these questions in earnest, to be fully informed finally of the background of our complicated situation," he added.

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AQUINO: JUST 'GOOGLE SEARCH'

In a statement Friday, Aquino said Cayetano's questions over his administration's handling of the maritime row "could be easily answered by a quick Google search."

"Further, as Secretary of Foreign Affairs, you have at your disposal the files and relevant personnel concerning the issue," Aquino said in a statement.

The former chief executive explained that while records and news reports of his administration's dealings over the maritime row are readily available, these would not explain the "very thinking behind our actions."

Aquino went on to remind Cayetano that it was under his administration when the Philippines sealed its victory in an international arbitral court which invalidated China's sweeping nine-dash claim to the waters.

• Int'l court backs PH on dispute vs China

"We, a small nation, were able to clarify and assert the rights of all before a superpower, China," he said.

China has disregarded the ruling and has continued militarization and island-building activities in the waters.

Aquino also explained that answering all of Cayetano's questions point-per-point would be similar to presenting a "playbook" or a "gold mine of information and intelligence" on the Philippines' strategy.

"That would make us predictable. I believe that would indeed make your life and our country's position more difficult should a similar situation arise down the line," he said.

"Alan, I remember you as being very fond of basketball. I ask: Would it be wise to give your team's playbook to your opponent?" he added.