Official cost estimates for the government's plan for electronic border systems have gone up by almost 80 per cent since the start of the pilot two years ago.

The trial of the eBorders scheme to log and check every passenger travelling into and out of the UK has resulted in more than 1,000 arrests since it began in 2004, says the Home Office.

But the full project is now expected to cost about £1.2bn over 10 years, compared with estimates of £1bn over 15 years in July 2005. And setup costs - the bulk of which are for technology implementation - have increased from £400m to £534m.

Despite the rise, the scope of the scheme is largely unchanged.

'We will transform immigration controls, bringing together plans for ID cards and electronic border controls, combining biometrics, information and risk assessment in a triple ring of security: overseas, at the border and in the UK,' says the Regulatory Impact Assessment published last week.

The report also outlines the requirements eBorders will put on the transport sector, with £72m-worth of capital investments and 10-year running costs of £322m.

Airlines will be the most affected, with anticipated investment of £52m and £278m of the running costs.

British Airways says it welcomes improvements to border security but the question of expenditure is still under debate.

'All parties are concerned about cost and it needs to be discussed,' said a BA spokesman.

Suppliers Raytheon and BT lead the two consortia on the shortlist for the eBorders deal, due in September.

The system is scheduled to be fully operational by 2010.

[Additional reporting by Dave Friedlos]