The International Monetary Fund (IMF) and World Bank have accused Singapore of reneging on a deal to allow activists into their annual meeting.
A small area has now been set aside for designated protests
The World Bank said it was "very displeased" with Singapore's decision to bar 28 activists from the country.
The Bank and IMF argue the presence of pressure groups is key to improving the work of financial institutions.
Singapore says it has banned the activists as they have taken part in "disruptive protests" in other nations.
"The most unfortunate thing is what appears to be a going-back on an explicit agreement," World Bank chief Paul Wolfowitz told about 50 activists in Singapore ahead of the annual meetings.
"So far we've had no satisfactory explanation why," he added.
The institutions added that they were particularly unhappy with the bans as they had signed an open access agreement in 2003.
"We work with these representatives of civil societies, and we value their role - even when we disagree with what they say," a statement from the World Bank added.
Singapore had banned public protests for the duration of the IMF and World Bank meetings amid concerns they could lead to violence and damage to property.
Following the ban, pressure groups and non-governmental organisations decided they would demonstrate on Batam Island instead - an Indonesian island located close to Singapore by boat.
However, Singapore has now set aside an indoor area where activists can gather to express their views.
But the designated protest area could become more than a little cramped as it is only an eight metre by eight metre square.