Former premier Dr Mahathir Mohamad has begun circulating a letter to the country's ruling party claiming his right to question the government amid alleged attempts to stifle him.

The letter is being distributed to some three million Umno members, whom Mahathir said were prevented from hearing his views after a series of party speaking engagements were cancelled.

"What are they afraid of? This is what worries me," Mahathir told reporters after speaking at an Umno local division meeting west of Kuala Lumpur.

"I think they are trying to hide something, that's why they don't allow people to hear," he said, referring to the government, whom he accused of "an abuse of power".

Where is freedom?

Copies of the letter were available at the meeting, the first Umno event Mahathir has addressed since the start of a bitter row earlier this year with the government of Prime Minister Abdullah Ahmad Badawi.

The former leader said in the letter that several local Umno divisions and groups had retracted their invitations for him to speak under duress from the party, lead by Abdullah, also Umno's president.

"They tell me they are being pressured heavily. Where is freedom?" said the letter signed by Mahathir and dated Aug 11.

"Why is the leadership of Umno afraid to let Umno members meet and hear my explanations? They are in their hundreds, they have power, they have control over the newspapers and television," he said.