Bangladesh Home Minister Asaduzzaman Khan has suggested an Israeli link to the recent killings of secular bloggers and minorities.
He said an opposition politician had met an Israeli intelligence agent and there was evidence of an "international conspiracy" against Bangladesh.
He gave no more evidence. Israel says the claim is nonsense.
Critics say the government is in denial about the killings, most of which have been blamed on or claimed by Islamists.
Mr Khan's comments come a day after the wife of a senior police officer investigating the deaths was shot dead.
The governing Awami League has sought in the past to link the opposition to the attacks. Relations with the opposition Bangladesh National Party (BNP) remain fraught following the disputed 2014 general election.
Muslim-majority but officially secular Bangladesh has no diplomatic relations with Israel and supports the Palestinians.
Analysis: Waliur Rahman, BBC Bengali editor in Dhaka
Any vilification of Israel will certainly please the vast number of Bangladeshis who support the cause of the Palestinians and bring some political dividends for any Bangladeshi party.
But the government is facing critical questions internationally, especially about the investigation into the series of killings.
Only one murder has so far come to trial.
While the government sees a conspiracy to block the country's advancement, Islamist groups continue to grow in strength and strike almost routinely at one of the state's basic tenets - secularism.
"Bangladesh has become the target of an international conspiracy. And a foreign intelligence agency has joined the conspiracy," Mr Khan said.
When asked to elaborate, he said: "You must have noticed that an Israeli intelligence agent had a meeting with a politician, it does not need to be verified further, all Bangladeshi know about it."
Israeli Foreign Ministry Spokesman Emmanuel Nahshon told the BBC the suggestion of Israeli involvement was "utter drivel".
Opposition MP Aslam Chowdhury was recently arrested and charged with sedition after he was pictured meeting Israeli government adviser Mendi Safadi in India.
Mr Chowdhury described his visit to India as a business trip and has denied meeting an Israeli intelligence agent.
The latest violence was in the southern port city of Chittagong, where Mahmuda Aktar was stabbed and shot in the head on Sunday in front of her six-year-old son.
Her husband, Supt Babul Aktar, is investigating the banned Islamist Jamayetul Mujahideen Bangladesh group (JMB) and she has been a prominent campaigner against religious extremism.
Also on Sunday, a Christian grocer was hacked to death in the north-western village of Bonpara. So-called Islamic State (IS) said it was behind the murder of Sunil Gomes.
Police say more than 40 people have been killed since January last year in the wave of attacks on those seen by extremists as offensive to Islam.
The government insists that IS does not have a presence in Bangladesh and has tended to blame the opposition and local militant groups.
Critics have accused the government of failing to properly address the violence in Bangladesh.
Who is being targeted?
The grim list of those who have fallen victim to attacks by Islamist militants in Bangladesh is growing ever diverse.
Secular bloggers, academics, gay rights activists, and members of religious minorities including Shia, Sufi and Ahmadi Muslims, Christians and Hindus have all been killed, many of them hacked to death.
When a university professor whose family said believed in God was murdered in April, it suggested the list of those at risk had widened further.
Who exactly is behind the attacks remains murky. Bangladesh has myriad extremist groups and there have been few convictions over the attacks.
Bangladesh has disputed claims by so-called Islamic State or al-Qaeda-linked groups for the attacks, instead often blaming opposition parties or local Islamist groups.
But until the killings stop the government itself will face accusations of not doing enough to protect minorities in the Sunni-dominated nation.