* FTSE 100 down 0.8%, FTSE 250 down 0.3%
* Burberry jumps after Q2 results
* 3i drops after H1 report
* FirstGroup marks worst day in more than a year (Adds news items, updates to close)
By Shashwat Awasthi and Muvija M
Nov 14 (Reuters) - London's FTSE 100 underperformed its major global peers on Thursday, suffering its steepest intra-day drop so far this month as falls in private equity company 3i, stocks trading ex-dividend and a stronger pound hammered the exporter-heavy index.
The main index fell 0.8% with 3i Group hitting a five-month low after striking a cautious tone about new investment opportunities and as heavyweight components Sainsbury , Shell and GSK traded without dividend entitlement.
The mid-cap FTSE 250 was 0.3% lower, with transport operator FirstGroup dropping nearly 20% on its worst day since May 2018 after a bigger first-half loss due to a charge related to its Greyhound bus line business in the U.S..
Dollar earners were among the top drags on the main bourse as sterling strengthened on hopes that Conservatives will win a majority in the December election and finally break the deadlock surrounding Britain's departure from the European Union.
Luxury brand Burberry outperformed the index, rising 3.4% as the popularity of designer Riccardo Tisci's collections boosted quarterly sales and offset declines in Hong Kong where trading was hit by ongoing protests.
A host of trigger points, including weak Chinese factory output data, anxiety around U.S.-China trade, and political uncertainty in the U.S. amid an impeachment inquiry into President Donald Trump also weighed on sentiment globally.
Slowing Chinese factory output growth was another sign of how Beijing's trade dispute with Washington was weighing on demand. To that end, China said the countries were holding in-depth discussions on a "phase one" trade agreement.
"If a deal doesn't go through in the next couple of weeks, the optimism seen in financial markets will rapidly turn into pessimism and I wouldn't be surprised to see a 5-10% correction in equity markets," said Hussein Sayed, Chief Market Strategist at FXTM.
"At this stage, markets are in a wait-and-see mode until further developments emerge."
G4S lost 2.4% after Norway's central bank said the country's wealth fund, the world's largest, can no longer invest in the security services company because of the risk that it contributes to, or is responsible for human rights violations.
Airport operator Stobart tumbled 5% on the small-cap index after suspending its dividend and posting a bigger first-half loss. (Reporting by Shashwat Awasthi in Bengaluru; Editing by Kirsten Donovan)