In the event of aggravation of an occupational disease for which a person suffering from such a disease has received or is receiving benefits under the legislation of a Member State, the following rules shall apply:

1. (a)

   if the person concerned, while in receipt of benefits, has not pursued, under the legislation of another Member State, an activity as an employed or self-employed person likely to cause or aggravate the disease in question, the competent institution of the first Member State shall bear the cost of the benefits under the provisions of the legislation which it applies, taking into account the aggravation;

2. (b)

   if the person concerned, while in receipt of benefits, has pursued such an activity under the legislation of another Member State, the competent institution of the first Member State shall bear the cost of the benefits under the legislation it applies without taking the aggravation into account. The competent institution of the second Member State shall grant a supplement to the person concerned, the amount of which shall be equal to the difference between the amount of benefits due after the aggravation and the amount which would have been due prior to the aggravation under the legislation it applies, if the disease in question had occurred under the legislation of that Member State;

3. (c)

   the rules concerning reduction, suspension or withdrawal laid down by the legislation of a Member State shall not be invoked against persons receiving benefits provided by institutions of two Member States in accordance with subparagraph (b).