KUALA LUMPUR, Sept 15 (Reuters) - Fourteen senior Malaysian lawyers, scholars and rights activists said on Tuesday that the country's rule of law had been steadily undermined, citing events surrounding the ''summary sacking'' of former finance minister Anwar Ibrahim.

''There has been an ever steady and increasing disregard for and erosion of the rule of law and the principles of natural justice,'' they said in an eight-page statement entitled ''The Rule of Law Under Threat'' and issued to news organisations.

They cited a judge's decision to allow affidavits ''very detrimental'' to Anwar to be made public despite a counsel's objection to their release and the detention last month of a businessman friend of Anwar's under the Internal Security Act.

The act provides for detention without arrest.

Prime Minister Mahathir Mohamad sacked Anwar on September 2. Mahathir said the former deputy prime minister and finance minister, under investigation for sexual misconduct and treason, was morally unfit, but provided no detailed reasons.

Mahathir said last week that Anwar would be indicted once police finished their investigations.

Anwar said on Tuesday that authorities had detained his former private secretary and he expected to be arrested later this month.

The former cabinet minister, who has repeatedly asserted he is being framed, said authorities were preparing 21 charges, including that of treason, against him and that he expected not to be allowed bail once arrested.

Among those who signed the statement were U.N. Special Rapporteur on the Independence of Judges and Lawyers Param Cumaraswamy, professor and human rights activist Chandra Muzaffar and former Bar Council chief Raja Aziz Addruse.

They said the judge who had banned distribution of a book detailing allegations of sexual misconduct by Anwar had been transferred to a post outside Kuala Lumpur, raising possible questions about the independence of the judiciary.

The statement said recent decisions involving contempt of court reflected a lack of sympathy on the part of judges for freedom of speech.

The 14 signatories said the activities following Anwar's sacking on September 2 ''followed the familiar pattern previously seen when this country had its constitutional crises'' in 1988 which led to the dismissal of the Supreme Court chief.

''Opinion was mobilised against Datuk Anwar to support the decision taken,'' the statement said.

''Just as at that time, no reasons were furnished by the prime minister for the dismissal but party stalwarts had no hesitation to agree with it.''