BEIJING (Reuters) - China's outstanding foreign debt fell by $51.7 billion in the first quarter to $1.36 trillion, the foreign exchange regulator said on Thursday, as local firms repay their dollar liabilities amid expectations that the yuan will depreciate further.

Foreign debt at end-March fell 3.6 percent from the end of 2015, after a 3.8 percent drop in the fourth quarter, the State Administration of Foreign Exchange (SAFE) said on its website.

The SAFE said in a separate statement that it expected the size of China's foreign debt to stabilize, and it would take steps to prevent risk from abnormal cross-border capital flows.

"Overall, the rate of decline in China’s outstanding foreign debt slowed by the end of the first quarter with risk of repayment under control," it said.

Short-term foreign debt stood at $849.1 billion at end-March, accounting for 62 percent of total debt and down about 8 percent from the end of last year, the regulator said.

Medium- and long-term debt, which made up 38 percent of the total, rose 4 percent from the end of last year, it said.

Yuan-denominated foreign debt made up 44 percent of the total foreign debt at the end of March, the regulator said.

The yuan <CNY=CFXS> has slipped about 2.3 percent against the dollar so far this year to more than five-year lows and is expected to weaken further as China's economy continues to slow.

(Reporting By Beijing Monitoring Desk and Kevin Yao; Editing by Kim Coghill)