Drugmaker Eli Lilly , which faces plunging sales due to competition and lapsing patents, will not merge with another peer to ride out any rough times ahead, chief executive John Lechleitr said on Saturday.

Speaking on the sidelines of a conference in Beijing, Lechleitr said he was confident the Indianapolis-based company can go it alone and invent sufficient new drugs to see it through.

Eli Lilly's resistance to any form of merger comes despite the fact that a series of patent lapses, stiff competition from generic drugmakers and regulatory setbacks are all set to hit its sales in coming months and years.

We are still very much opposed to a large-scale combination, Lechleitr told Reuters. We don't think size is necessarily supportive of innovation.

We feel that (with) our current size, with the sizeable investment in research and development, we have the way to generate new medicines we need to replace the medicines that we are losing, that are coming off patent in the next several years.

Many analysts expect Eli Lilly's earnings to fall steadily from this year through to 2014 as it loses patent protection on many of its best-selling drugs.

For instance, the U.S. patent on its biggest product, the $5 billion-a-year Zyprexa schizophrenia treatment, lapses in October.

Eli Lilly is among a handful of big drugmakers bent on staying independent in the wake of mega-mergers in the pharmaceutical industry from 2009, that saw Pfizer Inc

gobbling up Wyeth, and Merck & Co buying Schering-Plough.

A dearth in new drug development and looming patent expirations had forced the drugmakers to band together.

To bolster its earnings prospects, Lechleitr said Eli Lilly would increasingly focus on its animal health unit, one of the bright spots in the firm and where growth has far outpaced that in the core drug business.

Just this month, Eli Lilly said it will buy Johnson & Johnson's animal health unit for an undisclosed sum to augment its presence in Europe.

Lechleitr said Eli Lilly was open to buying other animal health businesses if the price is right.

We are going to be on the lookout for acquisitions if they fit with the needs that we have, and if they are available at the right price.

(Reporting by Koh Gui Qing; Editing by Kim Coghill)