Virtual networks are considered today as a critical IT resource that connects distributed and virtualised Cloud services and components like servers, applications and storage. Network virtualisation allows traffic isolation between different tenants, security, efficient migration of virtual machines and reduced cloud service management complexity. One of the goals of this work is to develop a multi-objective Virtual Network (VN) embedding algorithm for optimal placement taking into account constraints such as power consumption, availability and load balancing. Adaptive provisioning is also required to maintain virtual networks in cloud environments and deal with user mobility, resource re-optimisation and to respond to anomalies, faults and evolving demands. An exact adaptive fault-tolerant embedding algorithm to cope with node and link failures in cloud networks is also proposed. The embedding problem is formulated and solved as a mixed integinteger program. Performance of the proposed algorithms is reported