The world's two largest economies borrowed the most in the first quarter as global debt rose to a record above $305 trillion, while the overall debt-to-output ratio declined, data from the Institute of International Finance showed on Wednesday.

China's debt increased by $2.5 trillion over the first quarter and the United States added $1.5 trillion, the data showed,

The lack of transparency has also become a burden for emerging markets, where total debt is approaching $100 trillion from $89 trillion a year ago.

The global debt-to-GDP ratio fell to 348%, about 15 percentage points below the record set a year ago, with major improvements seen in European Union countries.