(For a live blog on European stocks, type LIVE/ in an Eikon news window) * FTSE 100 down 0.4%, FTSE 250 lost 0.3% Sept 29 (Reuters) - London’s FTSE 100 opened lower on Tuesday as worries about a stalling economic recovery against the backdrop of surging COVID-19 cases kept sentiment subdued ahead of the next round of Brexit negotiations and the first U.S. presidential debate. European Union negotiators signalled that they are willing to begin work on a joint legal text of a trade agreement with the UK, ahead of trade talks that resume on Tuesday, The Times reported. The blue-chip FTSE 100 index dropped 0.4% with banking stocks declining the most following strong gains in the previous session. The mid-cap index slipped 0.3% and was on track to record its worst month in five. Plumbing parts distributor Ferguson rose 6.3% to the top of the FTSE 100 after it restored dividend as cost-reduction measures, including job cuts and branch closures, and resilience in its main U.S. business helped it report a 4.1% rise in annual profit. (Reporting by Shashank Nayar in Bengaluru; editing by Uttaresh.V)