As part of its review, IMDA has put out a consultation paper on Oct 1 and feedback invited.
Last August, Tuas announced it will buy M1 from Keppel for an enterprise value of $1.43 billion.
While consolidation of the local mobile industry has long been flagged, StarHub, which operates a mobile network jointly with M1, has long been said to be the acquirer instead.
According to Keppel on March 26, IMDA's review of the deal "remains underway" and M1 and the Tuas are addressing additional queries from the regulator.
See also: Li Ka-shing eyes more telco sales in ‘cash is king’ strategy — Bloomberg
The deal, which was aimed to be closed within six months after the sale and purchase agreement, has been extended to May 21, or another mutually-agreeable date.
Keppel shares closed at $12.27 on March 26, down 1.45%. Tuas, quoted on the ASX, closed at A$6.18, down 0.32%.
