LONDON, May 30 (Reuters) - London-listed drugmaker Shire is considering a bid for New Jersey-based NPS Pharmaceuticals, FT Alphaville reported on Friday citing sources.

Shire has been working with advisers and held internal discussions about a potential cash offer for NPS, a rare disease specialist, valuing the business at just over $4 billion, the Financial Times blog said.

Shares in Nasdaq-listed NPS were trading 15.5 percent higher at 1500 GMT giving the company a market capitalisation of $2.92 billion. Shares in Shire were trading down 1.4 percent.

(Reporting By Anjuli Davies, editing by Steve Slater)