A team of plain-clothes security police wait outside the room where Premier Wen Jiabao is delivering his annual press conference.
The squad has been issued with small fire extinguishers, perhaps in response to the spate of self-immolations in protest at what some see as China's occupation of Tibet.
More than 20 Tibetan monks and nuns have set themselves on fire in last year, mainly in south-west China.
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Cloud and outbreaks of rain will ease away eastwards during the morning, clearing the east coast around midday with sunny spells developing.
Police and emergency services are attending the scene.
Rebel-held east remains at risk while the pumping station supplying the western part of the city is once again in operation.