A surge in home transactions ahead of tighter rules propelled new mortgages in Shanghai in May to more than double the monthly average in the first four months of this year.

Shanghai banks lent 10.8 billion yuan (US$1.7 billion) of mortgages last month, up 5.52 billion yuan from April and 10.3 billion yuan more than May last year, the Shanghai headquarters of the People's Bank of China said in a statement yesterday.

New mortgages in Shanghai have risen for four consecutive months by May and the monthly average between January and April was nearly 4.8 billion yuan, according to official data.

"Mortgages continued to significantly increase last month due to a surge in property transactions earlier this year," the statement said.

The central government announced on March 1 tighter measures, including a 20 percent capital gains tax, which immediately sparked transactions of both new and existing homes.

It usually takes banks two months to approve home loans so the data lag sales.