Algiers - Algeria has ramped up security along the borders and at energy facilities countrywide, but concerns linger over safety at the In Amenas gas plant one year after dozens died in a bloody hostage attack.
Heavily armed Islamists stormed the isolated Tiguentourine complex, which lies deep in the Sahara desert, on 16 January 2013, with 38 hostages killed in a four-day siege and army rescue operation that followed.
All but one of those who died were foreigners.
The North African country is heavily dependent on its energy sector, with hydrocarbons accounting for more than 97% of export earnings.
But despite the security reinforcements, al-Qaeda-linked militants remain a serious threat throughout the Sahara region, adding to the concerns of foreign firms which Algeria relies on to maintain production at its ageing oil and gas fields.
A top US general warned last week that Mokhtar Belmokhtar, the veteran jihadist who masterminded the hostage raid, had the capability to stage "another attack like In Amenas".
Belmokhtar's breakaway al-Qaeda group "Signatories in Blood" claimed the attack, saying it was in retaliation for France's military intervention against Islamist militants in Mali.
Norwegian firm Statoil, which jointly operates the plant along with Britain's BP and Algeria's Sonatrach, has returned to the country but not the site, where one of three production trains damaged in the attack is still out of action.
Statoil lost five employees, and only one of the 12 survivors is prepared to go back to In Amenas.
"It's a shame because I would have preferred it if there were others. But that's how it is. It's important that the families of my colleagues have their say," Kolbjoern Kirkeboe, 52, told AFP.
BP and Japanese engineering firm JGC, which alone lost 10 employees, are still waiting to return to In Amenas, where an inspection is planned in the coming days to assess the site's security, and the possible go-ahead.
To better protect expatriates working at the complex, which lies 1 300km southeast of Algiers, a landing strip is being built to provide a safer passage to and from the site.
Statoil has barred its employee from spending the night there until the new security measures are in place.
Kirkeboe was in the bus ferrying workers from the site that came under attack at the start of the raid.
Algeria refuses to allow foreign companies to organise their own security arrangements at the sites where they operate.
That task is entrusted to the Algerian military, which was criticised at the time for its handling of what was one of the worst hostage bloodbaths in years.
Sonatrach's chairperson Abdelhamid Zerguine said in October that the security of all its production sites, including those operated with foreign partners, was "guaranteed by the country's security authorities".
Statoil experts had concluded in a report published the previous month that security at In Amenas had relied too heavily on the Algerian army.
"Neither Statoil nor the joint venture could have prevented the attack, but there is reason to question the extent of their reliance on Algerian military protection," the report said.
The energy-rich North African country has dramatically increased security at its oil and gas installations since the attack, and along the vast porous borders its shares with Libya and Mali.
Military sources, cited by independent Algerian daily El-Watan, indicated recently that 20 000 troops had been deployed along the country's eastern and southern frontiers, with another 1 500 combing the region day and night, assisted by continuous air cover.
"Military command has sent the majority of its aircraft to Ouargla and Tamanrasset [in southern Algeria] as the main bases for intervention," said one of the sources.
Helicopters and Seeker II drones equipped with hi-tech reconnaissance equipment are able to carry out surveillance missions and precision air strikes.
There are indications that Algeria's heightened security arrangements are paying off, with several Islamist convoys having been destroyed between Tamanrasset in the far south and Illizi in the southeast, according to the military source.
In October, the army announced that it had seized a large weapons cache near the Libyan border, 200km from In Amenas.