Budapest, Dec 19 : Hungarian Prime Minister Viktor Orban and Turkish President Recep Tayyip Erdogan signed an agreement here elevating the bilateral ties to "priority strategic" level. Orban on Monday told a joint press conference following the signing of the agreement that "in the language of diplomacy, this expresses the strongest possible friendly, brotherly and political cooperation". Speaking of bilateral economic ties, Orban said that the volume of trade in goods has doubled over the past 10 years, with 500 Turkish companies operating in Hungary and 100 Hungarian companies in Turkey, Xinhua news agency reported. He added that Turkish investments in Hungary are continuously increasing both in number and value, extending to new areas, such as railway development and defence industry agreements. Orban emphasised the importance of Turkey in Hungary's security, especially in managing migration. "Turkish-Hungarian relations are friendly, with long-standing roots, and both sides have the intention to expand them," Erdogan said. Earlier on Monday, Hungarian President Katalin Novak received Erdogan, and later in the day, they also held talks. Seventeen agreements covering various areas were signed during the Turkish President's visit. Beyond commerce, energy security took the forefront, with mutual agreements in natural gas transit and procurement. Turkey will become a source for Hungary's natural gas purchases next year. Erdogan concluded the visit by attending the opening concert of the joint Hungarian-Turkish cultural season. /IANS