On every side there are signs of increased repression by the Sunni al-Khalifa royal family, which monopolises power in a country where Shia make up 60 per cent of the population. Between 2,400 and 3,000 people are in jail. In recent weeks, 50 Shia, including human-rights activists, were given up to 15 years in prison after the briefest of trials. Yousif al-Nashmi, allegedly tortured when detained by police, died in hospital soon after his release. The public prosecutor’s office said “the deceased was admitted to hospital on September 23 in a critical condition and was diagnosed with Aids”.

Two points have become clear during the 30 months since mass protests began on 14 February 2011: The protesters have not been cowed by persecution and the government has responded by turning Bahrain into a repressive police state. After tentative and unfulfilled promises of dialogue and reconciliation at the end of 2011, the monarchy reverted to reliance on force to crush the opposition. Significantly, the UN Special Rapporteur on Torture, Juan Mendez, has been twice denied entrance to Bahrain, most recently in April. A critic of the regime living in Bahrain, who did not want his name published, said that “over the last year torture has once again become the norm for anybody detained”.

Sensitivity to the degree to which Bahrain has apparently turned into an island of hate, with chasm-like divisions between rulers and ruled and between Sunni and Shia, was illustrated by the over-heated official reaction to President Obama’s reference to Bahrain in his speech to the UN General Assembly on 24 September. He had spoken mildly of “sectarian tensions that continue to surface in places like Iraq, Bahrain and Syria”, but Bahraini ministers queued up to deny that Bahrain had anything in common with Syria and Iraq. Interior Minister Sheikh Rashid bin Abdallah al-Khalifa, whose ministry is said to be importing industrial quantities of tear gas, said Bahrain had “never witnessed at any time sectarian tensions”. The Foreign Minister, Sheikh Khaled bin Ahmed al-Khalifa, claimed that the kingdom had fostered a culture of tolerance between different communities. He added that “what is occurring in Bahrain… is a concerted effort by terrorist extremist groups to target security personnel and expatriates with the intent of spreading fear and division”.

As with many authoritarian regimes over the centuries, the Bahraini government might find it difficult to ease repression even if it wanted to. The fears of the Bahraini Sunni community have been stoked by claims of the existence of terrorist plots inspired by Iran in support of its fellow Shia. But an independent inquiry led by the US-Egyptian legal authority, Cherif Bassiouni, on how Bahrain handled the unrest in 2011, found no evidence of Iranian involvement. Allegations of revolutionary intentions become self-fulfilling: Moderate bloggers and civil-rights activists who have been mistreated and given long sentences tend to be less moderate when they get out of jail.

Why have the al-Khalifas stepped up their efforts to crush the opposition over the summer? One reason is probably sheer frustration that 30 months after the first demonstrations at the Pearl Roundabout, protesters in Shia villages still confront police and hold marches. There is also an exaggerated perception in Bahrain – as in Saudi Arabia and in the other Gulf monarchies – that American power in the Middle East has declined more sharply than in fact it has. Thus the authorities felt free to arrest a prominent opposition leader, Khalil al-Marzouq, the Assistant Secretary General of al-Wefaq, the main opposition party, on 17 September. The opposition had hoped their leaders might enjoy limited protection because their detention would annoy Washington and Western Europe.

In practice, the US and UK have expressed just enough criticism of the Bahraini government over allegations of brutality and lack of democracy to not look too hypocritical when they denounce Syrian President Bashar al-Assad for torture and failure to hold elections. The international media largely ignored Bahrain from the end of 2011 because of competing crises in Syria, Egypt and Libya, but this disinterest is unlikely to continue. Foreign journalists and human-rights organisations are usually denied visas to visit Bahrain, but Amnesty International and Human Rights Watch have a better record than the foreign media in keeping track of arrests, imprisonment, torture and killings.

Hassiba Hadj Sahraoui, the Middle East and North Africa deputy director for Amnesty International, points out that Mr Marzouq’s arrest “is yet another blow to the National Dialogue which the authorities have been flaunting as a reason to cancel the visit of the UN expert on torture”. He also says that Bahrain’s allies can no longer mute their criticisms of abuses by pretending that this might derail a non-existent National Dialogue.

One government tactic is to try to stifle local media “Basically everything is banned,” says a Bahraini journalist. “Even the mildest criticism or report could put you in jail for terrorism for a long time.” A blogger, Mohammed Hassan, arrested at his home at 2am on 31 July, describes how he was beaten, given electric shocks and forced to stand for three days while he was punched and kicked until he signed a confession.

What will the outcome be for Bahrain? Having panicked and over-reacted at the 2011 protests the government has been unable to get back to sensible policies. Some observers believe the onslaught by security forces is to cripple the Shia community organisationally before offering a deal. A more ominous forecast is that the government is seeking to marginalise the Shia politically and economically while bringing in Sunni from Syria, Jordan, Iraq and Pakistan to take their place. Of 58 ministers and deputy ministers only nine are Shia, says a paper on sectarian cleansing produced by al-Wefaq, while of top jobs, directly under the king, just 1 per cent are held by Shia.

PATRICK COCKBURN is the author of “Muqtada: Muqtada Al-Sadr, the Shia Revival, and the Struggle for Iraq.