Spying activities on Malaysia by its allies is a serious matter, as it can strain the relations between Malaysia and these countries, which have been long established based on trust and sincerity, Malaysian Defense Minister Hishammuddin Hussein said Sunday.

"I believe if this (spying) is not fully explained, our long- established good relations can be adversely affected. Therefore, we need a full explanation on the extent of the spying activities and for what purpose," the minister told reporters here.

"Tensions can be avoided if the allies involved uphold the trust and sincerity in their relations with Malaysia," he said.

The spying issue arose following media reports on the claim made by intelligence informant Edward Joseph Snowden that the United States had 90 electronic surveillance facilities throughout the world, including at its embassy in Kuala Lumpur.

In light of this, Hishammuddin wanted a detailed explanation on the matter as such activities could threaten Malaysia's security and its other interests.

U.S. Ambassador to Malaysia Joseph Y. Yun was reported to have explained on the spying claim to the Malaysian government.