Qatar shares ended 1.4% higher on Tuesday, marking the index's biggest gain in nearly a month, after a breakthrough was reached in the country's three-year-old dispute with Saudi Arabia and three other Arab countries.

As part of the deal, Saudi Arabia would reopen its airspace and land and sea border to Qatar as Gulf Arab leaders arrived in the Saudi city of al-Ula on Tuesday for a summit focused on ending a long-running dispute with Doha.

Saudi Arabia, the United Arab Emirates, Bahrain and Egypt severed diplomatic, trade and travel ties with Qatar over allegations that Doha supports terrorism, a charge it denies.

The Gulf's biggest lender Qatar National Bank was the top gainer on the Qatari benchmark, adding 2.4%, while Qatar Islamic Bank tacked on 1.8%.

Saudi shares finished 0.2% higher, buoyed by a nearly 1% gain in Saudi Basic Industries Corp (SABIC), the world's fourth-biggest petrochemicals firm.

Lenders Al-Rajhi and National Commercial Bank gained 0.3% and 0.7%, respectively.

Oil prices rose by around $1 as tensions simmered following Iran's seizure of a South Korean vessel and as the OPEC+ group studied a possible production cut in February.

Elsewhere, the Dubai benchmark gained for a third successive session, putting on 1.2%.

The Dubai gains were led by blue-chip developer Emaar Properties and real estate firm Dubai Investments , which advanced 2.9% and 3.9%, respectively.

In Abu Dhabi, the benchmark strengthened 0.6% with telecoms major Etisalat adding 1.3%.

Activity in the United Arab Emirates' non-oil private sector grew in December as its Purchasing Managers' Index, which covers manufacturing and services, rose to 51.2 in December from 49.5 in November, a survey showed. The 50.0-mark separates growth from contraction

Bucking the trend, Bahrain's main index slumped 1.8%, dragged mainly by a 5.5% decline in Bahrain Commercial Facilities Co

Outside the Gulf, Egypt's benchmark firmed 0.2%. El Sewedy Electric Co tacked on more than 4%, while Ezz Steel Co put on 7.4%.