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* FTSE 100 up 0.9%, FTSE 250 adds 1.1%

Dec 29 (Reuters) - UK shares rose in thin holiday trading on Wednesday with defensive and financial stocks leading gains, against the backdrop of Britain reporting a record number of COVID-19 cases and slim prospects of pandemic-related lockdowns this year.

The blue-chip FTSE 100 gained 0.9% following a two-day Christmas break, while the domestically focussed mid-cap index advanced 1.1% at 0810 GMT.

Britain reported a record 129,471 new cases of COVID-19 on Tuesday, a day after Prime Minister Boris Johnson said he would not bring in new restrictions this year to limit the spread of the Omicron coronavirus variant.

Defensive sectors such as consumer staples that tend to be less sensitive to the economic climate boosted the FTSE 100 index. Reckitt Benckiser, Diageo and Unilever gained between 0.8% and 1.3%.

Banks added 0.9%, eyeing gains for the fifth straight week, as shares of HSBC, Barclays, Standard Chartered and Lloyds Group rose after the Bank of England raised its interest rate to 0.25% from a record low of 0.1% for the first time since the pandemic.

Drugmaker AstraZeneca rose 0.8% after closing an agreement with Ionis Pharmaceuticals to develop and commercialise a drug. (Reporting by Bansari Mayur Kamdar in Bengaluru)