Kuwait warned striking workers Tuesday that it could recruit outside replacements to confront a wave of labor unrest that has disrupted shipping traffic and threatens the Gulf nation's critical oil sector.

The extent of the disruption was unclear. An official at the state-run Kuwait Petroleum Corp. said Tuesday that exports of crude oil and other petroleum products were going ahead as normal, according to comments carried on the official state news agency.

Kuwaiti authorities have grown increasingly uneasy during a series of strikes begun last month by civil servants seeking greater pay and benefits _ on top of already generous perks such as free health care and low-interest personal loans. The protests mirror other instances of labor unrest rippling through the Arab world as part of a popular push for political and economic reform in the region.

Although Kuwait is OPEC's fourth biggest oil exporter, officials say the country cannot afford to significantly boost the payroll of its huge public sector.

On Monday, more than 3,000 customs officers joined the strikes, sharply escalating pressure on the government. The open-ended walkout froze shipping traffic in and out of ports and oil terminals. It also disrupted airport and land border crossing operations.

A union official told The Associated Press that the customs workers strike was continuing Tuesday.

"Still there are strikes. They have stopped their work and are waiting for a response" from the government, said Abderrahman al-Ghanim, secretary general of the Kuwait Trade Union Federation.

In response to the strike, a government crisis team was formed to take "all necessary measures" to keep key industries functioning, according to a report on the official Kuwait News Agency. The report quoted Minister of State for Cabinet Affairs Ali al-Rashed as saying one option would bring in replacement workers from "in or outside Kuwait to carry out duties in an appropriate manner."

Government officials in Kuwait told striking workers they would not consider any demands while walkouts are taking place.

The strike did not immediately shake oil markets with fears of supply disruptions. The U.S. benchmark crude oil contract for November delivery hovered above $85 a barrel early Tuesday in electronic trading.

The state oil company moved quickly to reassure customers.

Talal al-Khaled al-Ahmad Al Sabah, the company's managing director of government and parliamentary relations, said shipments were moving normally Tuesday. He told customers the company will meet their needs according to existing contracts, according to KUNA.

The strikes began last month after state oil workers received raises of between 15.5 percent and 66 percent after threatening to walk off the job. So far, strikes have hit banks and factories and almost grounded the state airline, Kuwait Airways, where union officials agreed to postpone discussions on walkouts until next month, media reports said.

Last week, a group of firefighters tried to storm the main fire department building to demand workplace changes.

The director of Kuwait's fire department, Maj. Gen. Jassem Al-Mansouri, said legal measures have been started against those involved in the "riots," the Kuwait News Agency said.

Kuwait has not been hit by major pro-reform demonstrations inspired by Arab uprisings, but the tiny Gulf nation stands out in the region because of its hardball political atmosphere. Kuwait's parliament has the most powers of any elected body in the Gulf, and opposition lawmakers openly criticize the ruling family.

In January, Kuwait's emir, Sheik Sabah Al Ahmed Al Sabah, ordered 1,000 dinar ($3,559) grants and free food coupons for every Kuwaiti.

Those handouts have been since dwarfed by other Gulf rulers trying to use their riches to dampen calls for political reform. Saudi Arabia's King Abdullah has pledged about $93 billion for more government sector jobs and services. Last month, Qatar announced pay and benefit hikes of 60 percent for public employees and up to 120 percent for some military officers.

Kuwaitis are used to a cradle-to-grave social security system that has increasingly become a burden on the government.