ISLAMABAD, Pakistan — Ayesha Siddiqa, a scholar specializing in defense issues, never set out to write a blockbuster.

These days, though, her dense academic book about the growing political and commercial reach of Pakistan's once-revered military is the hottest read in the country.

Military Inc. hit stores in the midst of a political crisis that has enveloped Pakistani leader Pervez Musharraf, who took power in a 1999 military coup and serves as both president and army chief.

Musharraf moved this week to clamp down on protests against his government and coverage of the opposition by independent media. A striking feature of recent demonstrations has been protesters' use of anti-army slogans — a first in a country where the military has been respected.

The army, traditionally seen as less corrupt and more efficient than civilian institutions, has strayed too far into politics and business under Musharraf, says Habib Wahabul Khairi, a prominent Islamabad lawyer.

Despite a history of coups and meddling in politics, the Pakistani military has been a unifying force in a country torn by regional, ethnic and religious divisions. As recently as early March, before the current round of demonstrations began, Pakistanis viewed the military more favorably than any other institution, according to a poll by the Washington-based International Republican Institute.

Siddiqa's book answers taboo questions about the military — at the moment the general public has started to ask them.

Musharraf is under pressure to relinquish his role as army chief if he seeks another term. He has built loyalty among the officer corps by rewarding supporters in the military with plum assignments at government agencies, state-run companies, universities and sports federations. At Punjab University, professors protested after a dozen retired officers moved in to take administrative posts, according to Military Inc.

Middle-class professionals and civil servants are starting to feel squeezed. "There's a general running every institution," says human rights activist Aasim Sajjao Akhtar. "It's as if nobody else in the country is capable of doing anything."

Siddiqa's book examines the army's vast business empire, which includes restaurants, property development, bakeries, beauty parlors, trucking companies, cement makers and wedding halls.

Older veterans don't like what they see. "This is not the army I belonged to and was proud of," says Imdad Husain, 76, a Rawalpindi shopkeeper who served in the 1960s. "They're earning big salaries, but the people are crying."

Military Inc., the first book to explore the army's business holdings in depth, captures public dissatisfaction with a military that "has its hands in everything," says former Prime Minister Nawaz Sharif, who was overthrown by Musharraf.

Siddiqa says the Musharraf regime has tried to suppress distribution of her book and stifle publicity.

Without explanation, the Islamabad Club canceled her book-launch party a week ago. Hotels in the capital were warned not to allow her to hold the event, she says. In the end, she held it at the offices of a charity.

Newspapers across the country wrote about the cancellation, and Military Inc. became an instant best-seller. The popular Mr. Books shop here sold its 300 copies immediately after they went on sale last week. Owner Mohammad Yusuf says he spends half his day on the phone with customers trying to find copies.

The government's reaction has made Siddiqa a celebrity. "I didn't expect (officials) to be as stupid as they are," she says.

In recent days, senior Pakistani officials have warned they won't tolerate criticism of the military. Prime Minister Shaukat Aziz said last weekend, "Those who talk against the armed forces are the enemies of Pakistan."

Ahmed Reza Qasoori, a lawyer for Musharraf's government, said: "Anyone who is defaming the Pakistani army is an agent of foreign forces."

State-run media have broadcast vitriolic attacks on Siddiqa. "I've been called an Indian agent, an American agent, a British agent," she says.

The public, once respectful of the military, has come to see it in a different light, according to retired Gen. Mirza Aslam Beg, a former army chief of staff. Writing in the newspaper Nawa-e-Waqat, Beg said: "The masses for the first time have come to the conclusion that they are the real power and that power cannot be confined by the use of force."

Contributing: Zafar M. Sheikh