Bangkok's US$4 billion new airport has around 100 cracks in its taxiways and two runways, which will disrupt air traffic for several weeks as damage is repaired and delay the issuing of a safety certificate.

Thai Transport Minister Theera Haochareon said some incoming flights to Suvarnabhumi - "Golden Land" in Thai - have been delayed for seven to eight hours as portions of the west runway were closed for repairs this week. And repair work was to start on the east runway from January 27.

Four flights were kept waiting to land for so long that they had to be diverted to U-Tapao, a Vietnam War-era military airfield, near Pattaya where they could be refueled.

The problem has now led Thailand's aviation authority to hold off issuing an international safety certificate for the airport - the latest setback for the hub since it opened four months ago.

The certificate is not required by law for the airport to operate, meaning it can stay open while problems are resolved.

The Department of Civil Aviation had been scheduled on January 26 either to issue a permanent Aerodrome Certificate or renew an interim document awarded July 25. Instead it opted to postpone the decision.

The certificate assures that the airport meets the standards of the International Civil Aviation Organization.

DCA director general Chaisak Angkasuwan said the agency would wait until Thailand passed a law due within months requiring all airports to meet ICAO standards and then reassess the situation at Suvarnabhumi.

"Getting the certificate is not legally binding, so Suvarnabhumi can operate without such a certificate," he said. But he conceded the lack of one would hit confidence in Suvarnabhumi.

The regulator, Airports of Thailand, has set up an independent panel to investigate that problem.

Prime Minister Surayud Chulanont, meanwhile, warned travelers of disruption because of the investigation into the cracks. "Flights can still land, but passengers will have to experience discomfort."

He also said that cracks on taxiways meant not all aircraft could dock.

On that, an AOT official said passengers would instead be ferried by bus from the tarmac to the terminal.

The airport - built on a swamp - has been planned and under development for 40 years, with authorities hoping it would become Southeast Asia's largest aviation hub, serving 45 million passengers per year.

Besides the cracks, problems include inadequate toilets, seating and complaints of a lack of cleanliness.

The airport, a pet project of ousted prime minister Thaksin Shinawatra, has also been plagued by scandal, including allegations of graft in the purchase of bomb-scanning kit and awarding of taxi and parking concessions.

General Sondhi Boonyaratkalin, who led the coup against Thaksin, has expressed his embarrassment at the airport situation. A military source said he was asked about the problems in an interview with CNN but would not discuss it.

"I don't want to talk about this issue. It's such an embarrassing thing, it should not be disclosed to foreign countries as it is our internal problem, which we have to fix."