* Investors focus on hawkish central banks

* AO World gains on upbeat outlook

* Plus500 pulls FTSE 250 index higher

* FTSE 100 up 0.4%, FTSE 250 adds 0.6%

Aug 18 (Reuters) - The UK's FTSE 100 index rose on Thursday boosted by commodity shares, although gains were limited by a number of stocks trading ex-dividend and fears that rapid policy tightening by the Bank of England to tame inflation will trigger a recession.

The FTSE 100 ended 0.4% higher, with Chilean miner Antofagasta rising 2.6% to top the index as copper prices gained on hopes for solid demand in China.

Oil majors BP and Shell added 2.6% and 1.6%, respectively, tracking crude prices higher on robust U.S. crude stocks data.

The FTSE 250 midcap index closed 0.6% higher, lifted by a 5.8% rise in shares of Plus500 Plc, a day after the online trading platform posted a higher half-year profit.

The index had logged its worst one-day performance since June 30 in the previous session after data showed Britain's annual consumer price inflation jumped to a higher-than-expected 10.1% in July, fuelling bets of another big rate hike by the BoE next month.

"The Bank of England (BoE) remains painted into a corner, forced to become increasingly hawkish because of high inflation and a tight labour market, even as the economy rapidly slows," BCA analyst wrote in a note.

"A recession is now unavoidable given the magnitude of the inflation shock, which is leading to a toxic mix of tightening monetary policy and contracting real incomes."

Rising worries about a cost-of-living crisis have rattled markets this year, with the domestically-focused FTSE 250 index down 14.2% compared with a 2.1% rise in FTSE 100 which is more skewed towards global firms and defensive companies.

Meanwhile, Liz Truss, the front-runner to become Britain's next prime minister, wants to examine the roles of the country's three financial regulators as part of a review, a source close to her leadership campaign said on Thursday.

Among other stocks, AO World jumped 5% after the online electricals retailer reported full-year underlying earnings that topped analysts' estimates.

A handful of shares trading ex-dividend weighed on the blue-chip index, with miner Anglo American, lender HSBC and insurer Legal & General falling between 0.8% and 4.1%. (Reporting by Sruthi Shankar, Johann M Cherian and Devik Jain in Bengaluru; editing by Uttaresh.V and Sriraj Kalluvila, Kirsten Donovan)