Standard Chartered has been upgraded to a 'buy', from 'neutral', by Nomura, which says that the Asia-focused bank is delivering growth in a challenging environment."For investors looking for top-line growth within a UK & European banks sector where growth is often a scarce commodity, we believe that Standard Chartered remains well positioned for the long term," the Japanese broker saidNomura says that while Standard Chartered has risks to pre-impairment profits growth and impairments from inflation and tightening monetary policy in Asia economies, the broker highlights that consensus expectations and valuation of the shares have eased in 2011.Analysts said that the group has had a strong start to the year with broad-based growth, and remains confident in achieving double-digit income growth with flat operating leverage for the year.The target price is raised to 1,800p, from 1,770p.---BC