Tei was found guilty of bribery during the campaign for Tonga's general election last November.
The ruling was handed down by Justice Laki Niu reports RNZ Pacific.
Last week successful election petitions were filed against the former prime minister, Pohiva Tu'i'onetoa and internal affairs minister, Sangstar Saulala, and both men were found guilty of bribing voters while campaigning for the election last year.
Tonga's finance minister Tatafu Moeaki was also found guilty of bribery.
They have now all lost their seats in Parliament.