The letter came hours after the Union Cabinet expressed grave concern over the situation in the state with Prime Minister Manmohan Singh directing Patil to present an appraisal report on the situation at the next cabinet meeting.

The Prime Minister is also understood to have expressed anguish over the situation on which he had to face embarrassment during the recent India-EU Summit in Marseilles.

In the letter, the Home Minister is understood to have stated that enough paramilitary forces have been provided to the state since trouble broke out in December, 2007.

He told Patnaik to take effective measures to control communal violence and to apprehend elements that continue to stoke violence and hatred.

Giving details of the deployment of central para-military forces to the state, Patil said that merely continuing to ask for additional forces after every few days could not be a solution.

Patil pointed out that an MI-17 helicopter was positioned at Bhubaneswar from August 31 to September 11 even without a formal request from the state government to facilitate transportation of troops to control situation and evacuation of the injured.

The helicopter was again sent from September 17 to 26 at the request of the state government, he said, adding that the authorities did only recce and not use it even once for transportation of troops -- the primary purpose for which the state government had asked for retention of the aircraft.

Patil is said to have pointed out that required attention was not given by the state government to strengthen the police force and said out of five India Reserve battalions sanctioned for Orissa, the state had raised only one.

He also said the paramilitary forces have spared no effort in providing personnel even at the cost of withdrawing them from other states.

Patil told the Chief Minister that in December, 2007, the Centre had rushed 600 paramilitary force personnel while in February this year 400 more jawans were sent in addition to 2400 personnel already deployed there.

After the killing of the VHP leader Swami Laxmanananda Saraswati in August, 2000 more personnel were dispatched.

Briefing reporters after the Cabinet meeting, Information and Broadcasting Minister P R Dasmunsi said the Cabinet expressed serious concern on Orissa, particularly Kandhamal where ‘some organisations’ were actively taking part in the violence.

"The situation is very grave. The government is quite concerned," he said, adding that ‘Orissa government has to do more, which they are not doing’.

Asked whether imposition of President's rule in the state was discussed, he replied in the negative saying matters pertaining to the Constitution were not discussed arbitrarily.

Meanwhile, anguished over the situation in Orissa, RJD chief Lalu Prasad favoured invocation of a rarely used constitutional provision under Article 355 to check violence there.

"Our party's view is that the government has failed there. It is unable to protect citizens and attacks are continuing," he said.

Labour Minister Oscar Fernandes said a strong warning has been given to the state.