MADRID - Corporacion Financiera Alba CFA.MC considers a stake of between 20 and 25 percent in Spanish builder ACS as reasonable and sufficient, the financial holding's co-chairman said on Wednesday.

Between 20 and 25 percent of ACS is an adequate level for us to be able to be an active shareholder and participate in the management of the company. It's a reasonable and sufficient stake, Carlos March told journalists ahead of the company's shareholders meeting.

In response to questions about ACS' plan to increase its stake in power firm Iberdrola to 20 percent from 12.6 percent currently, March reiterated comments by ACS Chairman Florentino Perez on Monday that the buider is in no hurry to raise its stake.

ACS also sees a 20-25 percent stake in Spanish stainless steel tube manufacturer Acerinox as a reasonable level, March said.

Corporacion Alba currently holds 24.5 percent of ACS and 23.8 percent of Acerinox, as well as 16.5 percent of Clinica Baviera.

March was not optimistic about the impact of the global economic crisis on Spain, which he sees as having a hard 2009 mainly due to the steep downturn in the property sector after a decade long boom.

However, the crisis would provide investment opportunities for Corporacion Alba, the co-chairman said.

We could invest up to 200 million euros, he said.

(Reporting by Judy MacInnes; editing by Simon Jessop)