The trips were indirectly paid for with Swedish international aid money, reports newspaper Dagens Nyheter.
In an interview with the news agency TT, Aid and Development Minister Isabella Lövin (Green party) said it is nothing out of the ordinary that poor countries get their travel and hotel costs paid for by the Swedish state.
"These are some of the poorest countries in the world, the most vulnerable. They don't have the budget to do these kinds of trips to exchange experiences," Lövin told TT.
So, in August last year the UN-ambassadors of 27 small island nations came to Stockholm. The aim was, according to Lövin, to have a discussion in the wake of the Paris climate change summit - but also to talk about what priorities Sweden has for the UN Security Council.
"War and conflict is one of the foremost reasons for poverty and distress, for people dying and starving. Work to prevent conflict, which is what can be done at the security council, is part of the fight against poverty. And there is nothing strange about that," she said, when asked if it isn't remarkable that aid money is used for lobbying for a seat at the head table of the UN.
The ambassadors were hosted by the Dag Hammarskjöld foundation, which received SEK 14 million from Sweden's aid budget.
A Swedish business association that opposes corruption says to Swedish Radio News that if the trip was intended to influence the island ambassadors then it is "extremely dubious". It would be natural to draw a parallel with the questions raised around corruption in soccer association Fifa, says Helena Sundén, general director of the Swedish Anti-Corruption Institute.
In June the ambassadors of UN member states will vote to decide which countries will get one of the rotating seats on the UN Security Council. Sweden is competing with Netherlands and Italy for a west Europe place, for the term 2017-2018.
It would join the five permanent members of the Security Council: USA, UK, France, China and Russia, which are the only members to have a power of veto.