The extent of the disruption was unclear.
An official at Kuwait Petroleum Corp. said exports of crude oil and other petroleum products were going ahead as normal, according to comments carried on the official state news agency.
Oil exports are moving normally and it will meet all customer commitments, Kuwaiti oil minister and officials said in a bid to offset fears of disruption.
Crude oil and oil product exports out of the OPEC producer briefly stopped when customs union employees went on strike, blocking the clearance process necessary for vessels to depart and discharge.
But on Tuesday shipping sources said oil tankers were back on the move again, after port clearance for the stranded ships was obtained, while Kuwaiti oil officials assured customers of disruption-free exports.
“There won’t any shortage or delay or halt to any (crude) quantity that has been agreed upon with all countries and establishments outside Kuwait,” he said.
Earlier Sheikh Talal Al-Khaled Al-Sabah, spokesman for Kuwait’s oil sector, also said all customer commitments will be honored.
But neither minister Busairi nor Sheikh Talal specified the measures that enabled Kuwait to process customs documents while 3,000 customs employees pressed ahead with their strike.
“We are still on total strike, especially after the government’s statement which totally ignored us,” Ahmed Al-Enezi, the head of the customs employees union, said.
Kuwait’s cabinet said on Tuesday that it had appointed a committee headed by the country’s interior minister to take all necessary measures to run all state businesses that may be impacted by the strike, state news agency KUNA reported.
It did not say the government would negotiate with the customs union.
The country is currently witnessing a wave of strikes by many government employees, after the cabinet approved earlier this month better employment conditions for oil sector workers.
In late September, Kuwaiti Central Bank employees held a demonstration while employees of the Kuwait Stock Exchange agreed to delay a planned strike and gave authorities three weeks to meet their demands.
Shipping sources earlier said at least four tankers departed from Mina Al Ahmadi port, which handles the bulk of the country’s oil exports.
A second source confirmed there was at least one more oil tanker at Mina Al Ahmadi port, waiting for clearance to depart.
Oil tankers loading out of single point moorings, which are used for bigger vessels, are able to get customs clearance as agents act on behalf of customs officers, an Asia-based trader said.
He said vessels loading out of jetty, especially product tankers, were unable to get customs clearance as they require a customs officer to go onboard.
Kuwait also has operational oil export terminals at Mina Abdullah, Shuaiba, and at Mina Saud, otherwise known as Mina Al-Zour, according to the US Energy Information Administration.
Investors kept a close eye on the strike and were watching for any supply disruption from Kuwait, but the physical market impact was largely muted.
Refiners in Asia have not reported any major delays or disruptions in their shipments.
A government crisis team was formed to take “all necessary measures” to keep key industries functioning, according to state media.
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.”
But 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 US benchmark crude oil contract for November delivery hovered above $85 a barrel early Tuesday in electronic trading.
