SYDNEY, June 3 (Reuters) - Papua New Guinea's prime minister warned the Opposition not to "play politics" with the visit of China's foreign minister amid an election campaign, noting China is a major trade partner and the biggest buyer of the Pacific nation's key gas exports.

China's Foreign Minister Wang Yi will meet with Prime Minister James Marape on Friday, after meeting with his counterpart, in the final days of an eight-nation tour.

China was unable to gain consensus from 10 Pacific island nations for a sweeping regional pact on security and trade at a meeting on Monday, after several nations said it was too rushed and they wanted to consult the broader region.

The United States, Australia and New Zealand have expressed concern over Beijing's ambitions for a greater security and policing presence in the Pacific, after it struck a security pact with Solomon Islands.

Administered by Australia until 1975 and its nearest neighbour, Papua New Guinea is strategically positioned and rich in resources but largely undeveloped.

Papua New Guinea had a foreign policy of "friends to all and enemies to none", Marape said in a statement.

"China is the major buyer of our produce, and we will engage with them more in commerce and trade, as well as other aspects of our bilateral relationship going into the future," he said. China buys over 50% of all the gas produced in Papua New Guinea and "have given an undertaking to buy additional gas", he said.

Marape hit back at former prime minister Peter O'Neill, who is running for the top job, for criticising the timing of Wang's visit as he arrived on Thursday.

O'Neill told media the national election was held every five years and the campaign period should be preserved without high-level international visits, and no deals should be signed.

"The former prime minister knows very well not to play politics with the visit of an international leader to our country," Marape said.

Australia's Foreign Minister Penny Wong, who is on her second tour of Pacific island nations to pledge Australia's support since being sworn in last week, told ABC television she was advised it "wouldn't be appropriate to go at this stage" to Papua New Guinea because of the election.

Australia's new Prime Minister Anthony Albanese has been invited by Marape to visit after the election, Papua New Guinea's Post Courier newspaper reported on Friday.

Marape has called on political parties to restrain from violence in the campaign. He thanked Australia for its support for the election by printing ballot papers and air logistics to remote electorates through the Australian Defence Force, the Post Courier reported. (Reporting by Kirsty Needham; Editing by Lincoln Feast.)