Loomis Sayles, the U.S. fund manager that oversees funds worth $150 billion, said this week that it has been aggressively buying Irish government debt for what its vice chairman Dan Fuss calls its attractive yield and credit quality.

"We have a completely different view of Irish debt than the rest of the world," Fuss told the press this week. "The bonds have been and continue to be cheap. Their yield is attractive relative to the view expressed in the market on Ireland’s credit quality."

Fuss said the U.S. firm was a buyer in the secondary market and it took part in Ireland’s 1.5 billion euro debt auction, which means it now holds that much in Irish government debt.

In a move that made headlines last week, Fitch Ratings downgraded Ireland’s credit rating to A-plus from AA-minus and put it on a negative outlook, indicating that the deeper than anticipated cost of cleaning up the banks and uncertainty over the economy were strong factors.

Broadly negatives headlines after Moody's suggestion that it might downgrade Ireland drove up borrowing costs, putting even more pressure on the government who are stuck with a debt pile that looks set to hit 155 billion this year.