A failed plot to oust the Bangladesh government, by what the army described as "religiously fanatic" officers, has raised questions over the level of Islamist penetration in the military, analysts say.

The army -- Bangladesh's key secular institution -- said the plot was unearthed in December and involved some non-resident Bangladeshis, around 16 serving and retired officers and the outlawed Islamist outfit Hizbut Tahrir.

A major general, who heads one of the country's largest cantonments, was recalled to Dhaka, while two former officers including a colonel were arrested.

"I am worried because radical, extremist views within a disciplined and secular force is unexpected," said Delwar Hossain, a professor of Dhaka University, who teaches security issues and international relations.

"It can have profound implications," Hossain told AFP.

Bangladesh has had a history of political violence, coups and counter-coups since gaining independence in 1971.

Sheikh Mujibur Rahman, the country's first president and father of the current prime minister, Sheikh Hasina, was assassinated during his overthrow by the army in 1975.

Bangladesh was run by a military dictator again from 1982 to 1990.

Democracy was restored in 1991, but street battles between supporters of Hasina and her arch political rival, Khaleda Zia, prompted the army to step in again in January 2007.

Although the military regimes appeased Islamic activists by enshrining "absolute faith in Allah" in the constitution and making Islam the state religion, they always took care not to undermine the army's secular status.

Some observers queried how serious the latest coup plot actually was, and suggested the army's focus on it's "religious" nature was meant as a warning to Islamist factions within the military.

"It looks like it may not have been a coup, but rather a dissension or disorder, which the army has been struggling to overcome in its evolution as a disciplined force," said Ataur Rahman, a senior researcher at the National University of Singapore and an expert on the Bangladesh military.

"By talking quite openly about a failed coup... the military wants to send a clear message that it'll not tolerate any drift towards religious extremism," Rahman said.

Hasina's government, which came to power in early 2009, has faced repeated threats from Islamist groups.

Efforts to bolster the secular character of the Bangladesh constitution in June last year triggered angry protests by Islamic activists in the Muslim-majority nation.

Her government has also launched a series of war crimes trials -- related to the country's 1971 liberation struggle -- which have so far mostly targeted the leaders of the country's largest Islamic party.

"Some Islamists are obviously not happy with the trials," said Abdur Rob, a professor of North South University.

After news of the failed coup plot was made public Thursday, Hasina's ruling Awami League party promised that those involved would be "given exemplary punishment".

The Bangladesh Army has become the biggest contributor to United Nations Peacekeeping forces -- a lucrative programme that observers say has reduced the appetite of rank and file army officers for political power.