As temperatures soar above 40 degrees Celsius (104 degrees Fahrenheit) in Aden, the great port city of south Yemen, homes become airless. Daily power cuts leave residents sweating through dark nights.

In a region where resentment of the government in the north has been festering for a decade, such daily indignities are enough to spark fury in the people.

Earlier this week thousands took to the streets in protest. Car tyres were burned, property vandalised and gun shots fired. Police were pelted with stones.

According to Yemeni officials this came after members of the opposition group known as the Southern Movement, some of whose factions call for independence from northern Yemen, ambushed a military patrol and wounded three soldiers.

The attack followed shortly on from the twice attempted assassination of an army brigade commander by members of the Southern Movement the week earlier.

In South Yemen scenes like these repeat themselves at increasingly shorter intervals.

Besieged by conflicts

Yemen's President Ali Abdullah Saleh is facing growing unrest

From his palace in the mountain capital of Sanaa President Ali Abdullah Saleh seems besieged by conflicts. To the north, a recent peace agreement quelling six years of rebellion by the Zaidi Shia Houthi clan, who fight a government they accuse of marginalising them politically as well as economically, has been breaking down, threatening a return to war.

In the unruly tribal strongholds of east Yemen Saleh's troops face an al Qaeda branch well integrated into the local community and whose failed attempt to bring down a US airliner last Christmas Day showed they are a menace not just to Yemen, but to international security as well.

However, to the government in Sanaa, no conflict is more serious than the growing power of the Southern Movement, whose call for independence from the north threatens the territorial integrity of the state.

Economic injustices

The key grievance levelled by the Southern Movement against President Saleh is economic: southerners complain bitterly that despite their small numbers, just 3.5 million compared to 20 million living in the north, and despite the south being home to the majority of Yemen's oil and gas fields (which account for 75 percent of the government's revenue) the south has not witnessed anything like the economic growth and development of the north, limited though that is.

The Movement accuses the president of favoritism of northerners, working through tribal patronage networks from which southerners are largely excluded, of arbitrary land confiscation and political disenfranchisement.

The grievances date back to the unification between North and South Yemen in 1990, which was viewed by many southern leaders as failed. They were politically outnumbered by their northern colleagues, the two armies were never integrated and assassinations of southern leaders created a deep mistrust of the north. After elections in 1993, leaders of former South Yemen called for a new federal constitutional system which would decentralize power.

Instead, a year later a brief but bloody civil war erupted with northern troops occupying the south. In the wake of the victory of north over south, President Saleh amended the constitution, removing institutions of joint north-south rule and granting himself power to rule by decree.

The Yemeni army is coming under increasing attacks from opposition rebels

Since then, a growing sense injustice has simmered in the south, but it was not until 2007 that the Southern Movement emerged, coalescing around a group of former South Yemen army officers, part of a group of 20,000 military personnel forced into early retirement after the 1994 war, who rose up after their pensions were not paid.

Former Brigadier Nasser al-Qawi from the Aviation Brigade of al-Anad Air Base was one of those officers and is today one of the Movement's leaders.

"The authorities' refusal to address the issues of the South, the looting of its resources for the benefit of the ruling family and the corruption have led [the South] to demand secession from the North," said al-Qawi in an interview.

He insisted that Southern Movement demonstrations had always been peaceful, but blamed Sanaa for a violent response. "It seems the authorities want to drag us towards violence to find a justification to suppress the movement."

"The language of violence and repression used against the people of the South reflects the failure and inability of the government to provide solutions. [...] For southerners the dream faded away and turned into a nightmare. People feel the South is under occupation by the North."

Read more about the volatile situation in Yemen

No head to cut

Even the use of force against the Southern Movement is not achieving the desired outcome

Since 2007 the Southern Movement has grown steadily. According to observers it has no unified leadership. "There is no central nervous system, which, paradoxically, has made it a lot more formidable, as there is no head to cut," said Abdul-Ghani Aryani, a Sanaa based political analyst.

The movement includes several political factions, most importantly the former ruling party of South Yemen, the Yemeni Socialist Party (YSP).

While many consider Ali Salem al-Beidh, who served as vice president of Yemen until he was forced into exile in Germany, the champion of their cause, some observers argue he is only a nominal figurehead.

Instead, they point to exiled Haydar al-Attas, former prime minister, as the most effective leader and former South Yemen President Ali Nasser Muhammad, who fled in 1986.

While the Movement's support base is mainly from the south, members of the Islah party, the northern-based Islamist opposition party, have also expressed backing for the Movement.

Sympathy for the Movement is even found among members of the president's ruling party, the General People's Congress (GPC). One former staunch supporter of President Saleh and the GPC, Tareq al-Fadhli, joined the Movement in 2009. A month later Nasser al-Wahayshi, leader of al Qaeda in the Arabian Peninsula (AQAP) announced his support for the Movement.

Whilst the defection by al-Fadhli, a former mujahedeen who allegedly fought alongside Osama bin Laden in Afghanistan and later against the YSP in the early 1990's was interpreted by some as the Southern Movement developing ties with al Qaeda, many see it as a deepening divide between the north and south.

"He was obviously disgruntled by the marginalization he and other southerners suffer from for the benefit of northern tribal elite," said Abdul-Ghani Aryani.

Neither evidence nor shared ideology has been found to link the Southern Movement to al Qaeda. Although al-Fadhli has stated that he supports an independent southern state, led by former YSP leader Ali Salem al-Beidh, he has recently been sidelined in the Movement.

Southern tribes such as the large Balharis tribe of Shebwa and the Bakazim of Abyan have also declared their solidarity with the Movement.

Cracking down

As the Southern Movement has grown the government in Sanaa has retorted with violence and repression. In an August 2010 report the human rights organisation Amnesty International accused Yemeni authorities of sacrificing human rights in the name of security.

The government is resorting to media repression to quell the unrest

The report argued that the government "has increasingly resorted to unlawful means, including enforced disappearances, unlawful killings, arbitrary detention and excessive use of force."

At the same time newspapers have been closed down, journalists, editors and proprietors detained, held incommunicado, ill-treated and jailed on spurious charges after unfair trials, said Amnesty.

"Journalists are in danger of arbitrary arrest by the state and are subjected to beatings and charges of causing riots in the streets," said Abdul-Khaliq al-Hout, who has worked for al-Diyar newspaper in Aden for six years.

Al-Hout said writing about the Southern Movement is a "complex" issue. "I can feel the lack of freedom of expression and of providing information and facts to the public."

Restrictive laws and the repressive practices of security forces and special courts have undermined freedom of expression in Yemen, though it is enshrined in the constitution. The Press and Publications Law of 1990 and the establishment of the Specialized Press and Publications Court in May 2009 have made it possible for the authorities to imprison "anyone who incites [ ] unrest."

Like many other journalists al-Hout was detained after writing an article about the Southern Movement. After two months in prison Human Rights Watch helped to secure his release. "There is a growing fear among journalists of the press court where journalists are treated as criminals," he said.

A revolution in the making?

Since the beginning of 2009, more than 66 people have been killed in or near demonstrations and 251 have been wounded. Fifteen members of the security forces have also been killed, according to media reports.

Analysts warn that as violence by government forces increases, so too does the call for independence. While some of their leaders have called for secession from the north, YSP, according to analysts, would consider federalism as would pro-Southern Movement elements within the Islah party. Members within the GPC have called for a local government in the south.

In response, on 22 May, the 20th anniversary of Yemen's unification, President Saleh called for a revival of national dialogue and offered to form a national unity government. According to Abdel Karim Aryani, a long-time adviser to the president, decentralization in the north and local rule for the south is being discussed. "This is what they [the Southern Movement] are asking for," he said.

However, the more radical calls for independence now come from the general population of the south who bear the brunt of the government's crack down. The president's olive branch was greeted with scepticism within the Movement which says it has been let down too many times before.

"It will not change anything. It will be written in pencil so it can be easily erased," said former Brigadier al-Qawi. "We have lost confidence in the government; their promises are always broken."

According to human rights lawyer Mohammed al-Saqqaf, local rule under a decentralised north may be too little too late: "Protesters repeat the same song they used to sing during the British rule: ‘Out of our country imperialism,'" he said.

"The depth of grievance in the south is such that they are unlikely to go away," said a Sanaa-based analyst, who did not want his name published.

With no central command the Southern Movement remains a fluid force. However, the analyst warned that if the cycle of violence in the south continues, what has until now been a disparate protest movement could merge and harden into an organized rebellion, tipping a low intensity conflict over into full-blown civil war.

"The emergence of a unified leadership is imminent, as soon as they turn to fully fledged violence, which is equally imminent."

Author: Annasofie Flamand, Aden

Editor: Rob Mudge