The Central Applications Office (CAO) website has resumed full service after a cyber attack this morning that restricted access for thousands of Leaving Cert students checking the first round of course offers.

The website was hit by what is believed to be a denial-of-service attack - which makes the service unavailable to intended users - at 6.10am, just 10 minutes after the offers were first published.

The CAO confirmed the site was fully functional again at 3pm and said it had launched an investigation.

CAO operations manager Joseph O’Grady said this morning the "malicious" attack came from an "unknown source" and urged students not to panic.

This afternoon, he said a technical solution had been found which would allow the resumption of a full service. "We will continue to monitor the website closely with the aim of ensuring the continuity of our online services for applicants," he said.

More than 23,000 online acceptances were recorded by the end of day, a thousand more than last year.

Students who accepted an offer today can log in to the CAO website over the coming days to confirm their acceptance has been recorded.

Acceptances can be also be made by post and the deadline for receipt is Monday, September 30th at 5.15pm.

In a denial-of-service attack, the targeted site is swamped with page requests to prevent it from responding to legitimate traffic.

Union of Students in Ireland president Gary Redmond called for a full investigation into the incident.

"It's unfortunate that the CAO website had issues this morning because obviously its a very stressful time for students," Mr Redmond said.

"An urgent investigation needs to be launched to ensure it never happens again and certainly doesn't happen next week when the subsequent rounds come out."

Labour Party education spokesman Ruairí Quinn said the attack would add to the anxiety applicants are experiencing. "I welcome assurances by CAO officials that they are working on the problem and would add my voice to appeals to students not to panic," Mr Quinn said.

The offers published this morning mark a return to a 1980s-style “points race” as record numbers of students seek a college place.

Two-thirds of the 70 most popular honours degree courses have registered an increase in points, according to a detailed Irish Times analysis. Points have moved upwards for virtually all higher-level courses in science, computing, agriculture, medicine and nursing.

The most striking feature of the first round is the points requirement for science at University College Dublin (UCD), up from 385 to 435 points, an increase of 50 points across a single year.

UCD science, which caters for about 400 students, is the largest course of its kind in the State. Three years ago, only 305 points were needed.

This year’s CAO figures represent a dramatic reversal of a decade-long trend where points have been falling.

The pressure on points is set to continue for the foreseeable future with the tighter jobs market forcing many school leavers and mature learners to opt for college.

Points could also rise again next year if the universities move to impose a cap on student numbers.

Higher Education Authority chief executive Tom Boland has signalled this cap may be necessary because of the financial crisis facing the colleges and the need to contain costs.

This year, arts at UCD, the largest undergraduate course in the State with more than 1,200 places, is up five points to 365.

Overall, there are 70 higher-level courses providing 70 or more places to students this year. This year, 45 of these have seen an increase in points, 10 are unchanged and only 15 show a fall.

In the second year of the Health Professions Admission Test entry route, points in medicine have risen virtually across the board, reflecting continuing confidence about job prospects for graduates.

Other main features of the CAO first round include:

* Teaching: No change in points for St Patrick’s Drumcondra (475*), despite the recent announcement of a further 1,000 primary teaching posts;

* Nursing: Points have increased yet again with general nursing up 15 points at NUI Galway, 10 at UCD (400*) and five at TCD (400*);

* Business: Points are up five for TCD’s business, economics and social studies (480*) but down 20 points in UCC;

* Social science: Social studies is up 15 at TCD to 465, while social science is up 20 at UCC to 390; and

* Science is up 25 points at NUI Galway (350*) and 20 points at TCD (460*). Biological and chemical science is up 25 to 375 points at UCC.

The Government will be pleased with the increased interest in science and related courses after years in which they struggled to engage students. This year, many appeared to be deserting business and related courses in favour of science courses with better job prospects.

As expected, points have tumbled for courses linked to the property market. Project and construction management at NUI Galway is down 30 points to 320.

The property crash is also having a knock-on effect on related courses. Civil and environmental engineering is down 55 at UCC to 430. Architecture is down 40 points at Waterford IT to 400 and by 60 at UL to 400.

The decline in conveyancing work is also having some impact on points for law, which are down five at TCD (515*). Points in many professional healthcare degrees including physiotherapy and radiography have also increased.

*An asterisk denotes not all students on these points will be offered places in round one.