Aden: When Islamists criticised a concert by a Syrian woman singer in Aden this month, disaffected southerners took it as yet another slight from their more powerful northern cousins.

Troops and police guarded the half-empty stadium when Asala took the stage, braving a reported threat from Al Qaida to stop the show, but she sang into the early hours with no disruption.

Still, the verbal sniping by Islamist parliamentarians from the north left a sour taste for many in the sleepy southern city, where performances by Arab pop stars are a novelty. "They've had concerts in Sana'a and Taiz and Hodeida before. Nobody opened his mouth," said Raqiya Humeidan, a woman lawyer, referring to northern cities. "Why is it different in Aden?"

Far less trivial grievances are fuelling discontent here, where many are once again querying the value of the 1990 union between the Marxist-led south and the tribal-dominated north.

Southerners complain they have lost out since unity in access to local power, jobs and land, and some even say they feel they have been subjected to a northern "occupation".

In recent months, protests spearheaded by former soldiers demanding pension rights have met a tough response from the security forces, with several people killed or wounded.

"They took our lands, our jobs and our wealth," Raqiya said. "We all feel they treat us with hate. So people are saying: 'If that's what you mean by unity, we don't want it'."

"Many people in the south now feel they have been unfairly treated," said Sarah Phillips, an Australian researcher on Yemen. "They feel that they have got these great resources and they are not seeing the benefits of them."

The owners of property nationalised under communist rule in the 1970s were to have been compensated after unity. "That didn't happen," said Abdul Gani Al Iryani, co-author of a paper on southern discontent published this month by the Washington-based Middle East Institute.

"Instead northern commanders, shaikhs and businessmen went down and, one way or another, secured over half the land in Aden and maybe 20 to 30 per cent of the agricultural land in [the province of] Abyan," the Sana'a-based analyst added.

Some protesters have demanded secession, but many southerners are merely demanding greater autonomy within a unified Yemen and less interference from the centre.

"We have never called for separation," said Bashraheel Bashraheel, managing editor of Yemen's leading independent daily Al Ayyam, which is based in Aden.

Many Adeni women say they had better access to education and jobs before unity, while some voice bitterness over rigid dress codes imposed by Islamists.

"After 1994 we went 100 years backwards," said a Yemeni staffer with a foreign aid agency. She asked not to be named.

Deputy Finance Minister Jalal Omar Yaqoub, himself an Adeni, said southerners had legitimate economic woes but their gripes about high prices and unemployment were shared across Yemen.

"The problems of unrest in the south are problems that exist everywhere," he said, adding that they only took a special form because they were politically exploited.

Al Iryani said southern anger ran too deep to be ignored and serious solutions must be found.

"If this doesn't happen, you will see further deterioration and then the situation in the south will cross a point of no return and then it will be very messy."