The move comes a week after she asked for talks about sanctions on Burma, officially known as Myanmar.
A Home Ministry source said the Nobel Peace Prize winner was driven to a state guesthouse where she met with the deputy heads of the US and Australian missions and the ambassador of Britain, who represented the EU.
It was the third time in six days Burma's military rulers allowed Ms Suu Kyi, 64, to attend meetings outside her lakeside home, where she is held under house arrest.
The National League for Democracy (NLD) party leader has been detained for 14 of the last 20 years and had her house arrest extended by 18 months in August for letting an American intruder stay at her home for two days.
She met with Labour Minister Aung Kyi, the designated junta go-between, on Saturday and Wednesday.
It was not known what was discussed in either of the meetings and officials would not be drawn on the purpose of Friday's talks with the diplomats.
