SINGAPORE - Asian ride-hailing giant Grab has launched what may well be its most aggressive campaign against the competition in Singapore.

In a text message targeted at ComfortDelGro cabbies on Sunday (Sept 3) night, Grab dangled a rental discount of more than 40 per cent to those who are willing to defect to any of the other taxi companies - all of whom use the Grab hailing platform.

"Dear Comfort Cabbie, HUGE Rental Discount deals from 4-15 Sept," the message read.

"$50 rental discount PER DAY, if you switch your taxi rental over to any of our taxi-fleet partners (TransCab, Prime, SMRT, Premier). No targets. No questions asked."

The discount - of around $1,500 per month - amounts to more than 40 per cent for Comfort cabbies who drive the Hyundai i40. Grab said those who switch to a private-hire car will get an even bigger discount - of $1,688 per month.

The salvo came a week after ComfortDelGro - Singapore's largest cab company - announced it was in exclusive talks with American ride-hailing company Uber about a possible tie-up.

It follows just days after Grab secured fresh fundings from Toyota Motor.

Neither ComfortDelGro nor Grab was available for comment.

Taxi-drivers interviewed said the discount was interesting but were mostly wary about switching.

Mr Alan Soh, 42, said: "What are the terms and conditions? Previously, when Trans-Cab had a similar offer, the terms and conditions were not favourable."

Mr Soh has been a cabby for 10 years, and has driven only for ComfortDelGro.

Competition in the taxi and private-hire industry is hotting up with operators battling one another to retain drivers as their cumulative fleet size approach 80,000 - three times what it was just four years ago.