* BMW sales up 9.4 pct vs 5.5 pct at runner-up Audi
* Six months sales gap with Audi more than doubles to 24,000
* BMW "has stronger momentum" than German rivals - analyst
BERLIN, July 8 (Reuters) - BMW's sales rose faster in June than at Audi and Mercedes as demand from China and the United States helped the German luxury car maker to extend a lead over its two main rivals in the first six months of the year.
Sales at BMW's core brand were up 9.4 percent in June to 153,000 autos, the Munich-based company said on Monday, compared with growth of 8.3 percent and 5.5 percent respectively at Mercedes and Volkswagen-owned Audi.
Six-month sales at BMW rose 7.7 percent to 804,000 cars, expanding the lead over runner-up Audi to 24,000 from 11,000 after five months. Half-year sales at Audi and Mercedes rose 6.4 percent each to 780,500 and 694,000 autos respectively.
"BMW has stronger momentum than Audi and Mercedes, that won't change in the second half," said Hanover-based NordLB analyst Frank Schwope. "Design of their cars has improved and they're ahead on fuel-saving technologies."
Still, Audi and Mercedes have each outlined plans to overtake BMW by the end of the decade.
In contrast to capacity cutbacks at European mass-market carmakers, Germany's three leading premium manufacturers are maintaining production in July and August to meet demand for upscale vehicles from overseas, rather than shutting factories for summer vacations.