The measure was designed to "improve liquidity in euro short-term markets," a brief ECB statement said.
The reciprocal currency arrangement, or swap line, "will remain in place as long as needed," it added.
On Friday, the Danish central bank raised its key interest rates by a half-point to 5.50 percent to support the beleaguered krone as
Like non-eurozone neighbors
The ECB swap agreement with Denmark follows one between the ECB and Hungary, where extensive borrowing in foreign currencies were a major contribution to that country's currently dire financial straits.