The National Assembly chapter of the Parliamentary Staff Association of Nigeria (PASAN)
The group had announced in a statement on Saturday that it would begin a four-day warning strike to commence on Monday.
The workers stormed the entrances to the National Assembly Complex in the early hours of Monday to barricade the gates and prevent entry.
More security operatives have been deployed to manage the protesters.
PASAN chairman Bature Mohammed said the decision of the warning strike was reached in an emergency congress held on Friday December 14.
President Muhammadu Buhari is due to present the 2019 Appropriation bill to the joint houses on Wednesday.
Members of PASAN had on December 4 shut down operations at the National Assembly when they prevented lawmakers from sitting.
The grievances of PASAN include a new condition of service for members, promotion and payment of 28