Cape Town - National Treasury could "in the extreme" try and block the R1.4trn takeover of SABMiller [JSE:SAB] by the world's largest brewer, Anheuser-Busch (AB) InBev, a senior Treasury official said on Tuesday.

READ: AB InBev buys SABMiller for R1.4trn in record deal

"We subject those applications to subjective criteria – the likely impact on capital account, the impact on the tax base and the possible complications," Treasury director general Lungisa Fuzile told Reuters.

The Food and Allied Workers Union (Fawu) said on Tuesday it would oppose the takeover over concerns jobs would be lost. "We as Fawu, and as part of the International Union of Food and Allied Workers, are certain that we will oppose this transaction using all available means and avenues," Fawu's general secretary, Katishi Masemola, said in a statement.

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.

READ: JSE cheers historic SABMiller deal

READ: What AB InBev’s £68bn acquisition of SABMiller means