Thousands of people in the country have lost their savings in an alleged investment scam.

Yayi's spokesman has previously denied the president's involvement in the case.

The president sacked his interior minister in July, accusing him of involvement in the company, ICC Services.

Analysts say the scandal threatens to cause turmoil in one of the most stable countries in West Africa.

Parliament's speaker has said the MPs' letter does not provide any evidence for a case against Mr Yayi.

The presidency has not commented on the letter, signed by 48 of 83 members of parliament, requesting Mr Yayi submit himself to trial for his alleged link to the fraud.

About 56 MPs would need to vote in favour of the motion for the matter to proceed.

ICC Services promised interest rates of up to 50%, but investors - many of them women with businesses - found they were unable to withdraw their funds.

Thousands of people took to the streets of the capital Porto-Novo last month, demanding the government help them reclaim their money.

Mr Yayi, a former development banker, won elections in 2006 promising to revive the economy and stamp out corruption.