Shafaq News/ Iranian President Ebrahim Raisi arrived in Islamabad on Monday on a three-day official visit, the foreign office said, amid tight security in the Pakistani capital.

The visit, which Pakistan's foreign office said would run until Wednesday, comes as the two Muslim neighbours seek to mend ties after unprecedented tit-for-tat military strikes this year.

"The Iranian president is accompanied by his spouse and a high-level delegation," Pakistan's foreign ministry said in a statement, adding that the group also included the foreign minister, other cabinet members and senior officials.

Raisi will meet Prime Minister Shehbaz Sharif and other officials, besides visiting the eastern city of Lahore and southern port city of Karachi, it added.

Major highways in Islamabad were blocked as part of the security measures for Raisi's arrival, while the government declared a public holiday in Karachi.

Raisi's visit is a key step towards normalising ties with Islamabad, but Iran's supreme Leader Ayatollah Ali Khameni, not the president, has the last say on state matters, such as nuclear policy.

Tension is also high in the Middle East after Iran launched an unprecedented attack on Israel a week ago and central Iran in turn suffered what sources said was an Israeli attack on Friday.

Pakistan and Iran have had a history of rocky relations despite a number of commercial pacts, with Islamabad being historically closer to Saudi Arabia and the United States.

Their highest profile agreement is a stalled gas supply deal signed in 2010 to build a pipeline from Iran's South Fars gas field to Pakistan's southern provinces of Balochistan and Sindh.

Despite Pakistan's dire need of gas, Islamabad has yet to begin construction of its part of the pipeline, citing fears over U.S. sanctions - a concern Tehran has rejected.

Pakistan said it would seek waivers from the U.S., but Washington has said it does not support the project and warned of the risk of sanctions in doing business with Tehran.

Faced with the possibility of contract breach penalties running into the billions of dollars, Islamabad recently gave the go-ahead for construction of an 80-km (50-mile) stretch of the pipeline.