President Park Geun-hye arrived in Seoul on Wednesday after a landmark state visit to Tehran focused on boosting bilateral economic cooperation with the resource rich country that is striving to generate growth through infrastructure investment.

The visit -- the first by a South Korean president in more than half a century -- represented South Korea’s efforts to tap into business opportunities in Iran, which has emerged as a promising market in recent months following the lifting of international sanctions.

Iran has announced about US$27 billion projects to build and modernize its infrastructure, including railways and airports.

On Monday, Park and her Iranian counterpart Hassan Rouhani observed the signing of nearly 20 out of 66 memorandums of understanding worth up to $45.6 billion after their summit.

Seoul hopes the MOUs could pave the way for South Korean companies to eventually win massive infrastructure projects under way in Iran.

Cheong Wa Dae, South Korea’s presidential office, has described the MOUs as the biggest-ever economic accomplishment.

Such a feat could give a big boost to Park at a time when she is struggling to push a reform agenda following the last month’s election rout by her ruling Saenuri Party.

Park also met with Iran's supreme leader Ayatollah Ali Khamenei.

The chief executives summit with Rouhani, meanwhile, was the first meeting between the leaders of the two countries since the establishment of bilateral diplomatic relations in 1962.

At the talks, Rouhani voiced his country’s opposition to nuclear development, in an apparent reference to North Korea's nuclear weapons programs.

It is rare for the Iranian leader to use strong rhetoric against North Korea, which is suspected to have cooperated with Iran in missile and nuclear programs.

The president's trip came amid speculation that North Korea could carry out a fifth nuclear test to mark a rare congress of the ruling Workers' Party scheduled to begin on Friday.

Park has repeatedly warned that North Korea’s provocations could hasten its collapse. (Yonhap)