Lufthansa, the parent company of low-cost carrier Germanwings, announced on June 30 that it would offer compensation of €25,000 ($27,000) to the families of each of 72 Germans killed in disaster in March.
In addition, each of the victim's immediate surviving kin — parents, children, adopted children, spouses and partners — would receive €10,000.
"You will not be surprised that my clients have told me to refuse this inappropriate offer," wrote Elmar Giemulla, who is advising 35 relatives of the German victims, in a document addressed to Germanwings' lawyer and seen by news agency AFP.
The lawyer called for the compensation for each victim to be "a six-figure sum", meaning at least €100,000, and the same amount for the victim's immediate kin.
Asked by German tabloid Bild for a specific figure, the lawyer said: "€25,000 per victim and €10,000 for the parents is not an appropriate acknowledgement of the suffering that has been inflicted on them. They are asking for an indemnity of €200,000."
Among the German victims were a group of school children from the town of Haltern who were returning from a school trip to Barcelona.
"The indignation (of the clients) is great," Giemulla told AFP. "We are waiting for a new offer" from Lufthansa.
The airline declined to comment on the matter when contacted by AFP.
Prosecutors believe that the jet's 27-year-old co-pilot Andreas Lubitz deliberately crashed the Airbus A320 into the French Alps on March 24, killing all 150 people on board.
After the crash, Lufthansa offered aid of up to €50,000 per passenger to their relatives, independent of any eventual compensation payments.
In addition, children and teenagers who had lost one or both parents would receive support towards their education from a special fund of up to €7.8 million.
In April, Lufthansa said $300 million in provisions had been earmarked to cover the damages.
The sum includes financial compensation for the families of the people who died and the cost of the Airbus A320 jet itself, which has a current list price of $93.9 million.