Bahrainis are calling their government’s intensified repression of all opposition “the Egyptian strategy”, believing that it is modelled on the ruthless campaign by the Egyptian security forces to crush even the smallest signs of dissent.

In recent weeks leading advocates of human rights in Bahrain have been jailed in conditions directed at breaking them physically and mentally, while others, already in prison, have been given longer sentences. The Bahraini citizenship of Sheikh Isa Qasim, the spiritual leader of the Shia majority in Bahrain, was revoked and the headquarters of the main opposition party, al-Wifaq, closed and its activities suspended.

Bahrain, once considered one of the more liberal Arab monarchies, is turning into a police state as vicious and arbitrary as anywhere else in the region. Mass protests demanding an end to the Sunni al-Khalifa dynasty’s monopoly of power during the Arab Spring period in 2011 were violently suppressed with Saudi military and financial help. The authorities agreed to an international investigation into what had happened that revealed widespread use of torture, unjust imprisonment and killings of protesters. Repression continued over the following five years but failed to eliminate entirely the protest movement, despite imprisoning at least 3,500 Bahrainis.

Brutalisation of these detainees has markedly increased in the past few months, a prominent example being the arrest of Nabeel Rajab, Bahrain’s leading human rights advocate. He was arrested on the 13 June on the grounds that he had made comments in the social media alleging torture in Jau prison and criticising air strikes by a Saudi-led coalition in Yemen. Rajab had been imprisoned for expressing dissent in the past, but this time he was placed in solitary confinement for 15 days.

Conditions in East Riffa police station, and later in West Riffa police station, to which he was transferred, appear to have been deliberately geared to break his morale, forcing him to use lavatories so filthy and infested with insects that he tried to eat very little so he would not have to visit them.

He lost 8kg in weight over 15 days in solitary confinement before he was taken to hospital where he was diagnosed as having an irregular heartbeat. His wife, Sumaya Rajaab, says the police did not allow the doctor to complete his examination before taking her husband back to same police station where he had previously been confined. “The authorities clearly intend to punish Nabeel Rajab by isolating him as if he were a dangerous criminal,” said Joe Stork, deputy Middle East director of Human Rights Watch. Rajab faces a 13-year prison sentence when he comes to trial on Tuesday.

He is not the only victim of enhanced mistreatment by the Bahraini security forces. Dr Abdul Jalil al-Singace, another human rights activist in Bahrain, has been in Jau prison since 2011 after he was sentenced to life imprisonment for allegedly plotting to overthrow the government in the Arab Spring protests demanding greater democracy. A polio victim who can only stand on one leg, he was nevertheless tortured at the time of his detention by beatings, sexual assault and being forced to stand upright for long periods despite his disability.

The Bahrain authorities promised improved conditions for prisoners at the time of the Bahrain Independent Commission of Inquiry in 2011, but recently his family have become worried that the Bahrain security forces are depriving him of his medications that he needs to treat his many disabilities, including post-polio syndrome. What is striking about the Bahrain government’s new campaign to suppress dissent is not only its cruelty but its pettiness such as, say Dr al-Singace’s family, depriving him of the rubber pads for his crutches.

Bahraini opposition leaders in exile say that the final decision by the authorities to systematically stamp out any remaining opposition in Bahrain was taken about two months ago. The security forces were influenced by the example of Egypt, where there are an estimated 60,000 political prisoners. Ali al-Aswad, a former opposition MP, says: “We have been told by a source that the heads of the security services have wanted to take a tougher line based on that being followed in Egypt for a year.

But the switch in Bahraini policy appears to have been triggered by a trip King Hamad bin Issa al-Khalifa took to Saudi Arabia. Saudi considers Bahrain to be very much within its sphere of influence and sent troops across the causeway to Bahrain in March 2011 to help end the Arab Spring protests.

The event indicating that the Egyptian model had been adopted came at the end of May when Sheikh Ali Salman, the leader of al-Wifaq opposition party, who had previously been sentenced for inciting hatred, disobedience and insulting public institutions, had his sentence increased from four to nine years. This was significant because the US and UK had been lobbying King Hamad to reduce the sentence or issue a pardon. US Secretary of State John Kerry had visited Bahrain in April and had raised the matter with the King.

It is unsurprising that Saudi Arabia should look for more aggressive action against the Shia majority in Bahrain because the island neighbours Saudi Arabia’s Eastern Province where the population is also largely Shia. With Deputy Crown Prince and Defence Minister Mohammed bin Salman wielding predominant political influence in Saudi Arabia, it has become more militant in repelling what it claims is an Iranian-backed Shia offensive against the Sunni.

The Bahrain government’s crackdown on dissent has proceeded swiftly and ruthlessly over the six weeks since Sheikh Ali Salman’s sentence was more than doubled. On 14 June the authorities issued an “expedited” instruction to close down the headquarters of al-Wifaq, seize its funds and end its activities. A day earlier, Nabeel Rajab had been arrested. On 20 June the citizenship of Sheikh Isa Qasim, the Shia spiritual leader, was revoked as has already happened to 300 other Bahraini citizens. Earlier in June another advocate of peaceful dissent, Zainab a-Khawaja, had fled abroad because she had heard she was about to be rearrested.

The Bahrain authorities probably calculate that the response of the US and UK to the effective ending of political and civil rights on the island will be mild. The US Fifth Fleet is based there and the UK is extending its naval facilities there with Bahrain footing the bill. The US lifted a prohibition on arms sales to Bahrain last year which had been in place since 2011. The British Foreign Secretary Philip Hammond has praised the Bahraini government’s “commitment to continuing reforms” and said it was “travelling in the right direction”.