CAPE TOWN (Reuters) - South Africa's National Treasury could "in the extreme" try and block the $106 billion takeover of SABMiller by the world's largest brewer, Anheuser-Busch InBev , a senior treasury official said on Tuesday. "We subject those applications to subjective criteria – the likely impact on capital account, the impact on the tax base and the possible complications," the treasury's Director General Lungisa Fuzile told Reuters. The deal to create a brewer making almost a third of the world's beer would rank in the top five mergers in corporate history and be the largest takeover of a UK company. SABMiller has a secondary listing in Johannesburg. (Reporting by Wendell Roelf; Editing by James Macharia)