By Matthew Miller

BEIJING (Reuters) - MasterCard Inc <MA.N> hopes to apply this year to become a payment service provider in China after the government opened the market, but the company is still weighing whether to do so alone or with a partner, senior executives said on Friday.

The world's most populous country is "pretty crucial" to its future, but MasterCard is still studying rules in China that would affect its business and is hammering out a business plan, Ann Cairns, president of international markets, told Reuters in an interview.

China in June allowed foreign payment card companies to operate in the country under new rules, potentially giving companies like MasterCard and Visa Inc <V.N> access to its 55 trillion yuan ($8.25 trillion) card payment market.

Under the rules, China's national security and cyber security standards must be met. Applicants must also hold 1 billion yuan in registered capital in a local company.

"We're trying to understand the rules," Cairns said, adding that MasterCard would like to enter China as soon as possible. "Certain things inside the rules – such as the new cyber rules, which need more development and understanding about how they’re going to work."

Visa and MasterCard, the world's two largest credit and debit card companies, have been lobbying for more than a decade for direct access to China's cards market, projected to become the world's biggest by 2020.

Asked if it was possible that MasterCard submits a license application this calendar year, Ling Hai, co-president for Asia-Pacific, said that was the hope but there were no guarantees.

"There is so much uncertainty and variability in the process. Something that should take one year can take two years," he said.

Bank card consumer transactions reached 55 trillion yuan in 2015, accounting for 48 percent of total social consumption, according to the People's Bank of China. The market is dominated by state-run China UnionPay Co.

Asked what was holding MasterCard back from jumping in, Cairns said it hinged on the business model and which local partners it decides to go with.

Cairns said capital requirements, security standards and for MasterCard to be locally based did not represent obstacles to the company.

MasterCard has never said it was under pressure to partner in China, according to Cairns.

($1 = 6.6690 yuan)

(Reporting by Matthew Miller; Writing by John Ruwitch; Editing by Ryan Woo)