Margret Wilson QC, chair of the Commonwealth Observer Group (COG) to Tonga's National Parliamentary Elections this year made the plea after being elected to lead the COG.
In a statement Ms Wilson said their task as observers is to consider all factors relating to the credibility of the electoral process as a whole.
"Accordingly, we are charged with observing and evaluating the pre-election period, the poll, the count and the declaration of the results," Ms Wilson said.
She said they will not interfere with the process and act impartiality, objectivity and independence.
"Each of us has been invited to participate in this assignment in our individual capacities and we do not represent the countries or organisations to which we belong," she said.
Ms Wilson said she was honoured to lead the observer group going into the Tonga General Election.