MADRID, Sept. 4 (Xinhua) -- The Spanish Defense Ministry has decided to stop the sale of 400 bombs to Saudi Arabia as they could be used in the ongoing conflict in Yemen, media reports said.

Sources from the Defense Ministry confirmed that the ministry has paralyzed the sale worth 9.2 million euros (10.6 million U.S. dollars).

The original contract to supply the weapons was approved in 2015 by the People's Party government of Mariano Rajoy and signed by then Defense Minister Pedro Morenes.

In an operation against Houthi rebels in Yemen on Aug. 9, Saudi bombs hit a bus, killing 51 people, 40 of whom were children,

The Saudi-led coalition admitted on Sunday "mistakes in compliance to the rules of engagement," and added that would "undertake legal proceedings to hold the ones who committed mistakes accountable according to the rules and regulations related to such cases."

The Spanish Defense Ministry made the decision 24 hours before Spanish Secretary of State for Commerce Xiana Mendez meets with members of the "Control Arms" coalition, which is made up of charities such as Oxfam, Amnesty International and Greenpeace and calls for "greater control and transparency" over the sale of Spanish made weapons.