Sweden, Israel, South Africa, Azerbaijan, Iceland, Portugal and Poland have been approved as prospective founding members of the Asian Infrastructure Investment Bank (AIIB), China's Ministry of Finance said on Wednesday.

The latest approval brings the number of prospective founders to 57, the ministry said.

Productive negotiations have been held among the prospective founders on the new bank's draft rules, according to official sources. The rules are expected to be finalized and signed in the middle of the year after a final session planned for May.

With an authorized capital of $100 billion, the AIIB aims at spurring investment in Asian energy, transportation, telecommunications and other infrastructures.

The bank is expected to be set up at the end of this year.