* Police tear gas quells new disturbance in Port Sudan
* Violent unrest spreading over fuel subsidy cuts
* Economic crunch caused by oil-rich South Sudan's secession
At least 29 people have been killed in protests in Khartoum over fuel subsidy cuts, police said on Thursday, and more clashes broke out in Khartoum in the worst unrest seen in Sudan's central regions for years.
President Omar Hassan al-Bashir, who came to power in a 1989 coup, has been spared the sort of Arab Spring uprising that unseated autocratic rulers in states from Tunisia to Yemen since 2011, but anger has risen over rising inflation and corruption.
A United Nations official told Reuters that Bashir, who also faces an arrest warrant issued by the International Criminal Court, would not be going to New York for the ongoing meeting of the U.N. General Assembly.
Sudan's foreign ministry denied that Bashir had decided not to attend at a time of instability at home, saying his request for a visa was still pending at the U.S. embassy in Khartoum.
A total of 29 people, civilians and police officers, have been killed, police said in the first official death toll.
Activists put the death toll much higher, in the dozens. A medical source at a hospital in Khartoum's twin-city Omdurman, speaking on condition of anonymity, said there were 27 bodies at his hospital alone.
Fresh clashes broke out in the evening between police and hundreds of protesters in Khartoum's north and Omdurdan, witnesses said. Officers fired tear gas into the crowds who hurled stones at police cars.
Thousands had marched in Khartoum on Wednesday, torching cars, buildings and petrol stations, prompting authorities to step up security significantly. Tanks and pickup trucks mounted with anti-aircraft guns were on the streets, while many petrol stations were closed.
In Port Sudan, the country's biggest port, police fired tear gas volleys to quell a small protest where participants chanted, "Down, down with the regime", according to witnesses.
The Arab-African country has suffered armed insurgencies in poor peripheral regions such as Darfur for decades, but the more prosperous central areas along the Nile including Khartoum have generally been relatively immune to unrest.
Similar protests broke out in June last year after some fuel subsidies were cut, but they fizzled out after a security crackdown.
The latest round of unrest began on Monday after the government announced another set of fuel subsidy cutbacks, causing pump prices to almost double overnight.
The cuts have been driven by a severe financial crunch since the secession of oil-producing South Sudan in 2011, which deprived Khartoum of three-quarters of the crude output it relied on for state revenues and dollars used to import food.
"SABOTAGE" AND CRIMINALS
Only about five newspapers reached kiosks on Thursday, carrying mainly statements from First Vice President Ali Osman Taha denouncing violence during the protests.
Editors at three newspapers said they had either been prevented from publishing by security agents or had decided not to print to protest at state attempts to steer coverage.
Journalists said security agents had ordered editors at a meeting on Wednesday to publish only the official version describing the protests as "sabotage". Still, independent daily al-Ahram published pictures of burned cars and buildings.
Information Minister Ahmed Belal Osman told al-Arabiya television: "This was not a real protest on Wednesday ... This was an attack on houses and to frighten citizens."
There was business as usual on state television, which showed soccer matches, musical performances and movies, and a police statement denouncing the violence was read out.
The state-linked Sudanese Media Centre said schools in Khartoum state would be shut until Sept. 30. Students have been at the forefront of previous rounds of anti-government protests.
Sudan's Internet was back up on Thursday, a day after being cut when activists started circulating pictures from protests via social media such as Facebook and YouTube, although those sites were still difficult to access.
A private sector telecoms official told Reuters the government had blocked the Internet without consulting telecoms firms, but the Sudanese embassy in Washington blamed what it described as damage of some telecoms facilities by protesters.
Bashir has remained in power for almost 25 years despite armed rebellions, U.S. trade sanctions, an economic crisis, an attempted coup last year and the warrant for his arrest issued by the International Criminal Court.