SOCHI, August 20 (RIA Novosti) - Russian President Dmitry Medvedev has told a first deputy prime minister to look into the situation concerning two merchant ships detained by China over debts, a presidential aide said on Thursday.

Chinese authorities detained the Vasily Yan cargo ship and the Professor Voskresensky vessel over debts by the owner of the ships, Russia's Arctic shipping company. Both vessels have been undergoing repair in the port of Shanghai since last September.

The crews appealed on Wednesday to the Russian president and prosecutor general to secure their return home.

Natalya Timakova said Medvedev also ordered Igor Shuvalov to "straighten out the debt claims" and see to it that the seamen have sufficient supplies.

The 21 crew members on board the two ships have not been paid since April 2009, and currently have insufficient reserves of food, fuel and drinking water.

The seamen demanded that the ship's owner pay the arrears and repatriate them.

The ship owner has yet to make an official comment.