AFP - The Malaysian and Thai prime ministers made a historic joint visit to Thailand's restive south on Wednesday, in a fresh bid to curb a raging separatist insurgency that has left 4,000 dead.

Najib Razak and his Thai counterpart Abhisit Vejjajiva officially named a "Friendship Bridge" spanning their shared border and visited an Islamic school in Thailand's troubled Muslim-majority southern provinces.

Security was tight amid a spike in militant attacks that has left 10 people dead since Monday, underscoring the challenges in finding a solution to the bloody six-year uprising.

Abhisit, who held talks with Najib in Bangkok on Tuesday, said the two countries were "strengthening our bonds" after years of mistrust over Thai allegations that Malaysia was failing to curb cross-border raids by militants.

"This Friendship Bridge will serve its noble purpose and boost further the various economic, social and cultural activities between our two countries," Najib said at the naming ceremony.

The two leaders arrived at the bridge near the Thai town of Bukit Ta in military helicopters. Thai army choppers circled the area and authorities cut mobile phone signals to guard against possible remote-controlled bombs.

Hundreds of Thai troops manned checkpoints leading to the border and bomb disposal squads checked the area, while police boats patrolled the Sunai Kolok River flowing below the bridge.

Najib later Wednesday visited a "widow village", set up by Thailand's Queen Sirikit, that shelters some 140 families affected by the unrest and teaches them handicrafts to make a living.

In the latest violence, one forensic policeman was killed and three security officials wounded in twin bomb blasts in Yala's provincial town early Wednesday.

Two Thai marines were wounded in a bomb and gun attack earlier the same day in Narathiwat province, where the bridge is located, after the troops tried to collect banners criticising Abhisit.

Another roadside bomb wounded two troops and a policeman protecting teachers in Yala province, while on Tuesday a bomb killed a soldier in a border town.

A soldier wounded in a clash with insurgents late Tuesday on a road due to be used by Abhisit and Najib died in hospital overnight, taking the toll from the incident to three security officials and one militant.

Four civilians died in bombings and shootings earlier in the week.

The rising violence has spurred Thailand to seek Malaysia's help in developing the impoverished region and improving education, depriving the shadowy militants of grievances that could drive new recruits into their hands.

Tensions have simmered in the region, formerly an autonomous Malay Muslim sultanate, since it was annexed in 1902 by mainly Buddhist Thailand. The current insurgency erupted in January 2004.

Thai Deputy Prime Minister Suthep Thaugsuban, who accompanied the two leaders to the region, said Najib's visit showed that Malaysia backed Thailand's efforts but that it also remained a domestic issue for Bangkok.

"The Malaysian government wants to join with the Thai government in development programmes that Thailand is employing in the south and support education projects that teach religion with a normal curriculum," he told AFP.

In Bangkok on Tuesday, Najib pledged his support for Thailand's "constructive" plans.

The bridge renamed Wednesday was opened in December 2007 by Abdullah Ahmad Badawi and Surayud Chulanont, the then-prime ministers of Malaysia and Thailand. Badawi did not visit any other parts of southern Thailand then.

Thailand has in the past accused Malaysia of failing to prevent insurgents crossing the porous 650-kilometre (400-mile) border, but the rhetoric has softened since Najib came to power in April.

Brussels-based think-tank International Crisis Group said Tuesday that Thailand should consider holding talks with the militants and must deal with the perceived impunity of security forces and disarm civilian militias.