Terming the decision as "unjustified", BJP said it would have a cascading effect on various sectors resulting in all round price hikes.
"It will increase all transport costs for passengers as well as on goods. It will increase costs of irrigation, tractors and other agricultural inputs," BJP spokesman Prakash Javadekar said.
He also dubbed as "farce" the decision to raise the cap on subsidised LPG cylinders from six to nine.
"Government must withdraw its decision and enforce the earlier regime allowing any number of LPG cylinders for domestic use," Javadekar said.
CPI(M) general secretary Prakash Karat said the steps towards deregulation of diesel prices will put additional burden on the common man.
"This will lead to continuous increase in the prices of diesel just as it happened with the prices of petrol after deregulation," he said.
Karat said the rise in the prices of diesel will impact on transport and increase inflation and also affect farmers adversely.
"The UPA government is adamant about further burdening the people who are already suffering from ever increasing price rise of all essential commodities," he said.
Karat said the decision to raise the cap on LPG cylinders to nine was insufficient and provided little relief.
CPI National secretary D Raja said, "The government's argument that this was done to face the fiscal deficit cannot be accepted as this deficit is due to its mismanagement of the economy. People cannot be punished for that."
Slamming the decision, Trinamool Congress leader Derek O'Brien said, "The Congress-led minority government is not managing the economy as much as damaging the economy."
He termed the hike in LPG subsidy as "all gas and gimmicks" and reiterated the party demand for 24 subsidised cooking gas cylinders per year.
Jaya slams deregulation of diesel prices
Slamming the Centre's move toderegulate diesel prices, Tamil Nadu chief minister Jayalalithaa on Thursday said it would pave the way for regular increase in prices of various commodities as oil companies have been authorised to revise prices periodically.
Holding that this decision,besides that of increasing the cap of subsidised LPG cylinders from six to nine was taken at the Cabinet Committee on Political Affairs in which union minister MK Alagiri of DMK is a member, she sought to know if he had opposed it "or kept silent as he could not understand the language or he did not attend the meeting."
"Following the Centre's decision to deregulate petrol, oil companies are periodically revising rates. The same is going to happen for diesel also. Subsequently whenever prices of the fuel goes up, it will also result in increase in prices, thus affecting the standard of life of the poor," she said in an official statement here.
Jayalalithaa observed that diesel price is generally controlled by the government to ensure that the price does not go up, affecting the common people.
She said the Centre, by deregulating diesel, was compounding problems of people, who are already suffering due to corruption, rising prices, inflation and increase in railway passenger fares.
The chief minister said diesel is an important part of the economy and a price increase would have a cascading effect of hike in prices of essential commodities,bus fares and others.
Jayalalithaa said the government was trying to escape criticism by increasing the LPG cap, but people had been demanding that cylinders should be supplied without any cap.
"DMK chief M Karunanidhi often talks about price rise.
But the CCPA in which Alagiri is a member has taken today's decisions. Did Alagiri extend support for these?Did he oppose? Did he keep quiet since he could not understand the language or did he not participate in the meeting?. Karunanidhi should explain this to the people," she said.
Jayalalithaa demanded that in the interests of the poor, the centre should roll back the diesel regulation and supply cylinders without cap.