It has been another bloody week in Bangladesh. A Christian shopkeeper, a Hindu priest and the wife of a prominent anti-terror security official were killed in separate attacks by assailants. On Friday, a monastery administrator enjoying an early morning walk in the north-western district of Pabna was hacked to death in a similar unprovoked assault.

In all, nearly 50 people have been murdered since 2013. Their offence? Not conforming to the fanatical faux-religious outlook espoused by Islamist extremists, for whom majority Sunni Muslim Bangladesh’s tradition of democratic, secular governance and multi-confessional inclusiveness is an abomination deserving of annihilation.

Such senseless mayhem obscures a bigger picture. Looked at in the round, Bangladesh is a success story. Since independence from West Pakistan in 1971, the country has risen from international “basket case”, as Henry Kissinger harshly termed it, to star performer in the UN’s Millennium Development Goals. Poverty levels have fallen dramatically, education and healthcare provision have vastly improved and a nation once prey to famine now produces a rice crop sufficient for 180 million people. Unlike many predominantly Muslim countries, women’s empowerment has also made enormous strides, symbolised by the fact both its current prime minister, Sheikh Hasina Wazed, and her predecessor, Begum Khaleda Zia, are women.

Despite this record of achievement, global media attention tends to emphasise the negative in what remains a relatively poor country. This narrative highlights climate change-related flooding, the damage inflicted by cyclones, exploitative labour conditions in the textiles industry (dramatised by the Rana Plaza factory collapse), corruption and poor governance issues.

The Hasina government’s crude attempts to constrain independent media reporting have invited further external criticism. The advent of a developing Islamist terrorist threat reinforces broader, unfair prejudices about Bangladesh in particular and Muslim countries in general.

That said, it behoves Hasina and her Awami League ministers to do more, urgently, to halt a spate of killings that is causing dismay at home and consternation abroad. The official position – that the government is cracking down on militants, which it is maintaining “heightened vigilance against home-grown terrorists and extremist outfits”, and that there is no evidence to support claims that Islamic State and al-Qaida are behind the attacks – is no longer tenable.

By their own admission, the authorities have achieved pitifully few convictions. The frequency and geographic spread of the attacks is increasing and widening. The range of targets is growing. And the freedom of action that the assailants seem to enjoy is giving rise to damaging talk of impunity or, worse still, collusion.

It is no longer acceptable simply to blame the problem on the main opposition party, the Bangladesh Nationalist party (BNP), and its Islamist ally, the banned Jamaat-e-Islami (JEI). Hasina claims the “BNP-Jamaat nexus” is deliberately attempting to destabilise the country by encouraging violence. Bad blood with Khaleda Zia, the BNP chair, runs deep. It dates back to the war of independence and its chaotic aftermath, when Hasina’s father, Mujibur Rahman, was murdered.

The role Jamaat played at that turbulent time, backing Pakistan against pro-independence groups, forms the backdrop to the international crimes tribunal launched by Hasina in 2010. JEI members have since been executed or jailed, including former leader Motiur Rahman Nizami, who was hanged last month.

Hasina’s domination of every corner of Bangladesh’s political space is pushing opponents to the shady margins. Nor is it credible for the government to continue to deny any link to international terrorism. Isis claimed responsibility for two of last week’s attacks. An al-Qaida affiliate, Ansar al-Islam, has claimed others. In inspiration and motivation, the killers who target secular bloggers, atheists, liberal academics, gays, Shia Muslims, other religious minorities and European nationals are clearly influenced by the wider struggle within Islam and between Muslim jihadis and the west.

Crime and punishment is not the sole issue here. At stake is Bangladesh’s tradition of cultural diversity, religious tolerance and secular governance. At risk is the future of a moderate Muslim nation battered by a destructive international political cyclone that it alone cannot control.

Observer editorial