B767-300 OVERSEAS FLT SUFFERS AN EICAS FLAP SLAT WARNING AFTER DEP. COMPANY SUGGESTS AND FLT DUMPS FUEL AND DIVERTS TO; LNDG OVERWT.

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AFTER DEPARTING RWY WE GOT A 'LEADING EDGE SLAT ASYMMETRY' EICAS MESSAGE AND A LEADING EDGE LIGHT ON THE FORWARD PANEL FOR ABOUT 30 SECONDS; THEN THE LIGHTS WENT OUT. AS WE RETRACTED THE FLAPS FROM 5 DEGS TO 1 DEG; BOTH LIGHTS CAME ON AGAIN AND REMAINED ILLUMINATED. WE CLBED TO A SAFE ALT AT 235 KTS TO STAY WITHIN THE FLAP OPERATING SPDS. ONCE AT A SAFE ALT; WE PERFORMED THE LEADING EDGE SLAT ASYMMETRY IRREGULAR PROC IN THE FLT MANUAL. WE ALSO OBTAINED VOICE COM WITH DISPATCH AS WELL AS MAINT COORD. AFTER CONFERRING WITH MAINT AND DISPATCH; IT WAS DECIDED THAT THE SAFEST AND MOST PRUDENT COURSE OF ACTION WOULD BE TO PROCEED TO AND LAND AT ZZZ AS THEY HAD THE BEST MAINT CAPABILITY TO HANDLE THE PROB ACCORDING TO MAINT AND ALSO AS WE WERE WELL OVER MAX STRUCTURAL LNDG WT. WE WERE VECTORED OUT OVER THE OCEAN TO CONDUCT FUEL DUMPING. WE DUMPED A TOTAL OF APPROX 19000 LBS OF FUEL. WE DECIDED THAT PROCEEDING INBOUND TO ZZZ AND LNDG OVERWT WAS A SAFE COURSE OF ACTION. WE LANDED AT 335000 LBS WITH A 12 KT HEADWIND USING FLAPS 20 DEGS AS PER THE LEADING EDGE SLAT ASYMMETRY PROC. ARPT CFR MET THE ACFT AND NOTED NO ABNORMALITIES; SO WE TAXIED TO THE GATE.