It is hard to agree with the Competition Commission of Singapore (CCS) that there is no evidence of a cartel among petrol companies here ("'No evidence of cartel' among petrol companies"; March 1).

The operating profits of all the petrol companies could have risen over the years because they have not been fully passing on the wholesale petrol price decreases to the consumers.

To validate this hypothesis and understand the source of the profit increase, the CCS should make transparent the changes in the various components of oil pricing, including operating profits of petrol companies.

It does not seem intuitively right that other components of pump prices, such as land costs and wages, could have risen fast enough to negate the effects of the drastic fall in oil prices.

Furthermore, if wholesale crude prices are indeed just one-third of the listed pump price, how do we explain the rapid increase in pump prices during times of rising crude prices, such as in mid-2009 or 2004?

In truly competitive markets such as the United States, petrol prices have mirrored the fall in crude oil prices and there is meaningful difference in petrol prices between various petrol stations.

The Singapore market, in contrast, sees similar prices across petrol pumps.

Bobby Jayaraman