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* FTSE 100 up 0.4%, FTSE 250 adds 0.1%

May 8 (Reuters) - London's benchmark FTSE 100 stock index opened at a record high on Wednesday led by AstraZeneca, after the drugmaker initiated a worldwide withdrawal of its COVID-19 vaccine, while investors awaited the Bank of England's interest rate verdict.

The mid-cap FTSE 250 gained 0.1%, set to rise for a third straight session. Both indexes have recorded consistent gains on a weaker pound that slipped 0.2% against the dollar.

AstraZeneca advanced 1.1% after the drugmaker said it initiated a worldwide withdrawal of its COVID-19 vaccine due to a "surplus of available updated vaccines" since the pandemic.

All eyes will be on the BOE's interest rate decision on Thursday, where it is widely expected to keep rates unchanged. However, dovish bets have risen recently, with markets pricing in a first rate cut in August.

Shell inched 0.2% higher, after the energy giant agreed to sell its refinery and petrochemical assets in Singapore to a joint venture between Indonesia's PT Chandra Asri Pacific and Glencore

J D Wetherspoon was up 3.6%, as the pub group forecast profit to be towards the upper end of market expectations, after it posted higher sales in third quarter. (Reporting by Pranav Kashyap in Bengaluru; Editing by Rashmi Aich)