* Angola LNG's return brings relief amid project delays
* Up to six more cargoes may be offered by Angola -trader (Adds company statement)
By Oleg Vukmanovic and Sarah McFarlane
MILAN/LONDON, June 6 (Reuters) - Angola's recently refurbished liquefied natural gas (LNG) export plant has launched a tender to sell its first cargo since it was unexpectedly shut down in April 2014.
According to tender document details relayed by traders, the cargo was loaded between June 3 and 5 on board the Sonangol Sambizanga tanker and bid submissions are due on the morning of June 13, trade sources said.
Angola LNG confirmed the first cargo since the shutdown had been loaded and was being sold via an international tender but did not give further details of the process.
The tender is valid until June 15, one source said, while a second trader said that up to six more cargoes could be loaded before the facility goes offline for a final phase of testing.
In the current tender, the delivery date of the first cargo varies according to the location of terminals dotted around the world.
For example, the Chevron-led project lists a six-week delivery window for Argentina's Bahia Blanca terminal - between June 28 and August 14, one trader said.
The cargo may be priced based on levels at Britain's gas trading hub, the National Balancing Point, or as a percentage of Brent crude oil, he said.
During the period the plant was shutdown LNG prices fell by around two-thirds to trade below $5 per million British thermal units (mmBtu) this year.
"The market has changed a lot while our plant has been shut down, but we are pleased to be able to deliver Angola LNG to the world and to take our place as a reliable and safe supplier in global LNG markets," Artur Pereira, chief executive of Angola LNG Marketing said.
Resuming supply from Angola may bring a measure of relief to buyers as delays to new projects and supply outages have helped to nudge spot LNG prices higher in the past few weeks.
The combined impact of these delays means there is less supply in the market than traders previously assumed, prompting some to cover short positions they otherwise intended to keep open.
Exports from Chevron's new Gorgon export facility in Australia are not expected to resume until the end of the month, industry sources said, following an unplanned shutdown in April.
Meanwhile, Houston-based Cheniere Energy has already said that the completion of its second production line at Sabine Pass would be delayed until August, from June.
And a second line at Origin Energy's AP LNG project is also running behind schedule, sliding from the third-quarter into the fourth, according to trade sources.
Angolan supply, although still slight by global measures, may help to allay any residual fears of supply tightness as Asian markets head into peak summer demand season, traders have said.
Chevron has a 36.4 percent share in Angola LNG, while Angolan state oil firm Sonangol has 22.8 percent. Other stakeholders include Total, BP and ENI . (Reporting by Oleg Vukmanovic and Sarah McFarlane, editing by Louise Heavens and Jane Merriman)