Lhasa - China can maintain its grip on Tibet "forever," a senior official said on Tuesday, but conceded that a heavy security presence was still needed to ensure order in Lhasa two years after deadly riots.

Hao Peng, deputy Communist Party boss and deputy governor in mountainous Tibet, fingered unidentified "anti-Chinese" forces and exiled spiritual leader the Dalai Lama as the main threat to a region which has been hit by sporadic unrest since 2008.

"We have the ability and confidence to maintain stability in Tibet forever, and we will ultimately achieve long-term order and stability," Hao told visiting journalists, in a city still tense two years after it was ravaged by deadly ethnic rioting.

"What you see in the streets, including the police and other legal forces, are necessary measures to maintain stability," he said, speaking in an ornate room in the Tibet government offices.

At least 19 people died in the March 2008 riots in Lhasa, which sparked waves of protests across Tibetan areas. Pro-Tibet groups say more than 200 people were killed in a subsequent crackdown.

Protests against Chinese rule, led by Buddhist monks, gave way to torrid violence, with rioters torching shops and turning on residents including Han Chinese and Hui Muslims.

Many Tibetans see Hans as intruders threatening their culture and religion, and say they have been treated harshly by the government since the riots.

Beijing has denied being heavy-handed, and says it has poured billions of dollars into boosting Tibet's development, money it says benefits mainly Tibetans.

Hao said peace had returned and blamed overseas agitators for the continued presence of armed police in Lhasa, especially in the old Tibetan quarter.

"The situation in Tibet is more stable than before the March 14 incident," he said.

"The Dalai clique and some anti-Chinese forces internationally have colluded to make trouble in Tibet. Because of this, we have to take a lot of measures, to ensure the stability of the legal system and the stability of Tibet."

Exiled Tibetans and rights groups say those in Tibet are living under difficult restraints and many are still waiting to hear from relatives and friends who disappeared after the violence.

"Two years down the line there is still no normality across the Tibetan plateau. It's still extremely tense," said Nicholas Bequelin, a researcher on China with Human Rights Watch, a New York-based advocacy group.

"It's still very difficult to get things done, there are still a lot of restrictions, a lot of surveillance, a lot of troops. Certainly tourism and travel is not back to normal."

The area is usually off-limits to foreign reporters, apart from those on rare and tightly-controlled government trips like the one Hao met with, which makes it hard to assess competing accounts.

NO DALAI LAMA PORTRAITS

Hao, repeating the government's standard line about on-off talks with representatives of the Dalai Lama, said China was willing to talk if independence was off the table.

"The core of this policy is for the Dalai Lama to abandon Tibet independence, stop separatist activities, and acknowledge that Tibet is an inalienable part of China," he said.

"If he does this then the door to talks is always open."

The Dalai Lama denies China's charges against him, and says he only seeks more meaningful autonomy for Tibet and that he has never advocated violence. China says it does not believe him.

But his image is not allowed to be shown publicly in what is officially called the Tibet Autonomous Region despite the reverence many Tibetan Buddhists have for him. Every year some make the dangerous trek to India and back to see him in person.

The Nobel Peace Prize-winning Dalai Lama fled into exile following an abortive uprising in 1959.

Hao said the prohibition on his image was natural. "The Dalai Lama is not merely a religious figure, he is also a mastermind of separatist activities. No sovereign country in the world would allow the hanging of a portrait of a person like that," he said.

(Writing by Emma Graham-Harrison, editing by Miral Fahmy)