4. Conditions relating to solemnization of foreign marriages.- A marriage between parties one of whom at least is a citizen of India may be solemnized under this Act by or before a Marriage Officer in a foreign country, if, at the time of the marriage, the following conditions are fulfilled, namely:--
(a) neither party has a spouse living,
(b) neither party is an idiot or a lunatic,
(c) the bridegroom has completed the age of twenty- one years and the bride the age of eighteen years at the time of the marriage, and
(d) the parties are not within the degrees of prohibited relationship: Provided that where the personal law or a custom governing at least one of the parties permits of a marriage between them, such marriage may be solemnized, notwithstanding that they are within the degrees of prohibited relationship.