The Centre on Tuesday hinted that the West Bengal government's delayed action contributed to the rapid spread of bird flu even as it allayed fears about the disease spreading to humans in the state.

In West Bengal, the administration set a daily target of culling three lakh birds over the next seven days from Wednesday in the seven affected districts -- Birbhum, Murshidabad, South Dinajpur, Burdwan, Nadia, Bankura and Malda.

"Initially, there was a delay of nearly a week's time for notices to be sent to us, but now things have been put on track," Union Health Minister Anbumani Ramadoss said on the sidelines of a function in New Delhi.

Asked whether the delay contributed to the disease spreading so fast, he said, "It could have been handled better."

On whether the disease has affected humans, he said, "To date, we have not got any confirmation for that."

Ramadoss said that the screening was conducted within 10 km of the affected areas and all people who live in the villages had been randomly tested.

"There is no reason to be concerned about any human cases of bird flu," Ramadoss said, adding "we are vigilant."

Union Animal Husbandry Secretary Pradip Kumar said in Kolkata that the strength of the expert teams would be raised from 500 to 600 to carry out the culling operations from tomorrow. He hoped the disease would be contained in seven days.