European Union (EU) has to remain vigilant regarding terrorist threat, the European Commission said?in Brussels?on Wednesday.

Europe has been shaken by a wave of bomb attacks these last few days, with terrorist bomb plots in Yemen and parcel bombs addressed to several European embassies in Greece.

"Terrorist threat is constant," the European Commission said on Wednesday. "We have to be aware that we have to remain active and vigilant both in the member states but also at the European level."

Following the recent terrorist incidents, the commission together with the Belgian Presidency will convene a special meeting of air safety experts of member states on Friday with the aim to evaluate the response to the recent threats.

No bomb parcel has been addressed to the European Commission yet, but a special procedure has been put in place in the building, urging receptionists and civil servants to refuse any parcel and to send suspicious packages to postal services where adequate equipment will be used to analyze the parcels.

The commission also reminded that the EU, together with the United States, has the strictest rules in the field of air safety and that the bloc is working closely with international partners, especially with the U.S., Canada and Australia.