SINGAPORE — Australian regulators and politicians must decide soon whether the proposed $8 billion takeover of the main stock market operator, ASX Ltd., by the Singapore Exchange is in the national interest.

The merger of the Asia-Pacific's fifth- and eighth-biggest bourses to create the world's fifth-largest securities exchange would offer investors access to the second largest listing venue in the region, with more than 2,700 companies from 20 countries on the combined platform, including more than 900 mining and natural resource firms and the biggest number of real estate investment trusts and exchange-traded funds.

The deal was initially opposed by the Tokyo Stock Exchange, which holds 4.9 percent of the shares in the Singapore bourse. TSE President Atsushi Saito said issuance of new shares would reduce the value of his company's stake, but the TSE subsequently dropped its criticism, citing growth prospects for the merged entity.