Siemens could win an expansion of its record 8 billion euro ($8.8 billion) power deal with Egypt, the German industrial group's chief executive said in a staff newsletter.

Joe Kaeser said Egypt, whose state-run electricity grid is creaking under the weight of fast-growing demand, needed extra capacity before the start of the hot summer months - faster than Siemens could build new turbines under the existing deal.

"We have a handshake on which we can build," he added in the interview with Siemens Welt seen by Reuters on Friday."

The extra capacity would be 800 megawatts, which would be produced by upgrading existing power stations and putting into place decentralised power-generation units, Kaeser said. He did not say how much the deal could be worth.

The 8 billion-euro deal signed in June was for 16.4 gigawatts and is designed to boost Egypt's power-generation capacity by 50 percent after going online in 2017.

($1 = 0.9086 euros)