A group of experts on international law voiced their doubts and concerns on Sunday over the South China Sea arbitration, warning the proceedings of the case are questionable.

Some 30 experts from Asia, Africa, the US and Europe exchanged views at a seminar co-organized by Leiden University's Grotius Center for International Legal Studies and Wuhan University's Institute for Boundary and Ocean Studies.

A wide range of issues were brought up on the arbitration case unilaterally initiated by the Philippines at the seminar about the appointment of arbitrators, the arbitral proceedings and its jurisdiction.

Abraham Sofaer, former US State Department legal adviser, said that China has made a clear declaration on exceptions that it does not accept any mandatory procedures, including arbitrations, with respect to disputes over sovereignty and delimitation of the sea area, therefore the unilateral arbitration proposed by the Philippines is a particularly unwise litigation.

Michael Sheng-ti Gau, a professor of international law at the Institute for the Law of the Sea of National Taiwan Ocean University, said most of the Philippines' claims in the case could be negated by the notes verbally issued by the two countries from 2009 to 2011.

The court failed to see that the Philippines' self-defeating claims were in fact over sovereignty, Gau said. "The court should deal with the real issues of admissibility and jurisdiction in all the claims of the Philippines."

Sienho Yee, chief expert at the Institute of International Law at Wuhan University, said there were previous international arbitration cases that involved territorial and delimitation disputes, but the court somehow ignored the rulings of those cases that could play in China's favor, adding that two of the five appointed arbitrators reversed their previous comments in favor of China without further explanation, which violates the consistency principle, an important component in international jurisprudence.

Sreenivasa Rao Pemmaraju, former chairman of the UN International Law Commission, said that no matter what the result might be, it would not help ease tensions in the disputed waters, as the ruling would only be an abstract academic exercise without true value in resolving disputes.