Bill Gross lifted the portion of Pimco’s Total Return Fund devoted to U.S. government-related debt to a five-month high in April.

That debt, which includes Treasuries, made up 36 percent of the world’s biggest bond fund in April, up from 33 percent in March. Total assets for the fund managed by Gross are $224.5 billion.

The fund’s holdings of non-U.S. developed nation debt slipped to 13 percent of its assets in April, down from 18 percent in March and the lowest level since November, Bloomberg reports.

Treasuries have soared in recent days, as investors fearful about the European debt crisis have turned to the U.S. government bond market as a safe haven.

The 10-year Treasury yield recently hit a five-month low of 3.20 percent.

"It’s a mini-relapse of a flight to liquidity, as hedge funds and other leveraged positions are liquidated to preserve capital," Gross told Reuters.

The turmoil in Europe will continue to buoy Treasuries, according to Gross’ colleague Mohamed El-Erian, Pimco’s CEO.

“This will amplify the impact of higher global risk aversion,” El-Erian wrote in an Email, according to Bloomberg.

“Some areas — like the U.S. Treasury bond market — will also feel the impact of capital inflows on account of flight-to-quality.”

Others agree. “There is serious concern about the pace of growth right now given the European concerns, and that’s supporting global bond markets,” Dan Greenhaus, chief economic strategist at Miller Tabak, told Bloomberg.