By Elaine Lies and Ami Miyazaki

TOKYO (Reuters) - The Philippines is a good place for foreign investment despite statements from its volatile president attacking the United States and worries about his foreign policy, Philippine Finance Secretary Carlos Dominguez said on Thursday.

President Rodrigo Duterte has thrown a long-standing alliance the United States into question since he took office in June, with a series of insults and threats to cut ties with the old colonial power.

While on a three-day visit to Japan this week, Duterte said he might end defense treaties with the United States.

Last week, in China, he announced his "separation" from the United States but then said ties were not being severed but he was pursuing an independent foreign policy.

Dominguez said the response to some of Duterte's statements had been overblown and the Philippines would welcome investment from the United States though it was particularly interested in trade agreements with Asian neighbors.

"We have looked around the world and said where should we redirect our economy, where should we integrate more," Dominguez told Reuters in an interview in Tokyo.

"We have a 600 million population market which is growing," he said, referring to Southeast Asia.

"We have China to the north, which is 1.3 billion which is growing very well, Japan has been a long time friend of the Philippines, and South Korea has been a very good partner."

After only some 100 days in office, Dominguez - a former agriculture minister and childhood friend of Duterte - said it was difficult to comment on trade pacts, such as the chances of a proposed free trade agreement with the European Union.

He said he was particularly interested in a Regional Comprehensive Economic Partnership (RCEP), a proposed 16-nation free-trade area of which China is a key driver, while he questioned a U.S.-promoted Trans-Pacific Partnership (TPP) bloc.

"I personally would like to look at the RCEP ... that one we are more open to. With regards to TPP, that's being reviewed all over, including in the United States, so maybe we'll put that on the back burner," he said.

He also said the Philippines would give "priority attention" to a free trade agreement with the European Union.

'NOT DIVORCE'

Duterte has praised relations with Japan during his visit and Dominguez said he hoped Japanese businesses, facing a labor shortage at home as the country ages, would establish small- and medium-sized companies in the Philippines to produce car parts and electronics.

U.S. investment was also definitely welcome, he said.

"What does separation mean? It's not divorce," he said.

"Somebody suggested it's more like a child leaving its home and establishing its own home."

When asked if he, as Duterte's childhood friend, could advise the world on how to work with the president, he said: "He's very focused on his goals and he doesn't appreciate being slowed down.

"He will lash out at people who try to slow him down."

Duterte was apparently infuriated when the United States questioned his bloody war on drugs in which about 2,300 people have been killed.

The United States has seen the Philippines as an important ally in its "rebalance" to Asia in the face of a rising China.

Duterte has instead made overtures towards China, which he visited last week, despite a bitter dispute over rival claims in the South China Sea.

(This version of the story corrects length of visit in paragraph 3)

(Reporting by Elaine Lies; Editing by Robert Birsel)