TAIPEI, Taiwan (Reuters)—Taiwan's insurance industry regulator will "soon" review the extra paperwork submitted by the buyer group of American International Group Inc.'s Taiwan unit and sees smooth communications with the U.S. insurer.

The insurance bureau of the Financial Supervisory Commission has received paperwork from Ruen Chen Investment, the buyer group, paving the way for a final decision on the much-delayed and often contentious $2.16 billion sale.

"We have very strong desire to complete the review as soon as possible," Huang Tien-mu, the bureau's director general, told Reuters in an interview on Tuesday. He declined to say by when a decision would be made.

"After the sale was rejected the first time, we and AIG have come to a better understanding (of our principles)... Both sides' communications are very smooth," he said.

The 18-month long saga of AIG's attempts to sell its Nan Shan unit in Taiwan has been marked by an extended push-me pull-you with regulators, union protests and even debate in parliament.

Along with slow progress in other foreign companies' sales of Taiwanese entities, it has raised concerns about Taiwan's regulatory environment.

The American Chamber of Commerce in Taiwan said in report in January that the environment was "inconsistent", while consultancy McKinsey, in a March report on private equity, noted that the "story in Taiwan is one of navigating a regulatory labyrinth."

In a rare response to the concerns, Mr. Huang said, "Taiwan has opened its insurance market to foreign investors since the early 1980s. We have always welcomed them, as long as they meet regulations."

Mr. Huang, a veteran regulator who chooses his words carefully, noted that Nan Shan has 4 million policyholders, or a sixth of Taiwan's population, meaning that special attention is needed when deciding on its future.

The first deal AIG struck was rejected last August, on the grounds that the-then buyer group did not meet the regulator's five conditions.

The head of Nan Shan told Reuters in an interview earlier in April that it will not seek a fresh sale of the unit if its second attempt is unsuccessful, underlying its determination to push through the deal.

Mr. Huang said this plan will not influence his deliberations.

"In this position, we face pressure from everybody every day. My mandate is to take care of things as soon as possible. I have not been in a situation where the pressure is too big to handle. Our top priority for now is to deal with the Nan Shan sale based on laws and regulations."

Mr. Huang said the regulator is also keeping a close eye on U.K. insurer Aviva P.L.C.'s plan to exit the Taiwan market.

"Aviva has not been in the market for a long time. I hope they will consider it carefully," said Mr. Huang.

Aviva, Britain's No.2 insurer, said in November it wants to pull out of its joint venture with First Financial , pending regulatory approval.